<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2023 Workiva-->
<!--r:a1bcc819-cc4e-40e3-ba23-8e40fd5e078c,g:ca82239f-2c73-41de-bafb-a428e0bfbf40-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedBalanceSheets" xlink:type="simple" xlink:href="mgni-20230930.xsd#CondensedConsolidatedBalanceSheets"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_4c11e954-f886-4a80-885c-ef723dc12a26" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_defd58ef-feb1-42f0-a6df-c40c6363fd0c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_4c11e954-f886-4a80-885c-ef723dc12a26" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_defd58ef-feb1-42f0-a6df-c40c6363fd0c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_6d54b4db-3cf1-455a-961d-c18770704fa3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_4c11e954-f886-4a80-885c-ef723dc12a26" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_6d54b4db-3cf1-455a-961d-c18770704fa3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_8e59eab6-2db3-433a-af7f-bb685811fc22" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_4c11e954-f886-4a80-885c-ef723dc12a26" xlink:to="loc_us-gaap_DebtCurrent_8e59eab6-2db3-433a-af7f-bb685811fc22" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_1392b5bf-f129-49f5-9414-5d389d1f79fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_4c11e954-f886-4a80-885c-ef723dc12a26" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_1392b5bf-f129-49f5-9414-5d389d1f79fc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_564de989-f85b-4dc5-965b-0abe17f67816" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_us-gaap_AssetsCurrent_564de989-f85b-4dc5-965b-0abe17f67816" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_4b93ffec-ca1f-4e63-8740-07b98c1ba13c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_4b93ffec-ca1f-4e63-8740-07b98c1ba13c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_a0de5b17-b97b-4373-963d-0e0fbff44de2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_a0de5b17-b97b-4373-963d-0e0fbff44de2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_InternalUseSoftwareDevelopmentCostsNet_c0bfdc04-e9e1-4836-8793-52d9f93aa6db" xlink:href="mgni-20230930.xsd#mgni_InternalUseSoftwareDevelopmentCostsNet"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_mgni_InternalUseSoftwareDevelopmentCostsNet_c0bfdc04-e9e1-4836-8793-52d9f93aa6db" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_668eb3f1-1e01-4305-a31d-f51382df2848" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_668eb3f1-1e01-4305-a31d-f51382df2848" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_d494edc5-9949-411e-8377-3371620578c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_d494edc5-9949-411e-8377-3371620578c2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_4cffbf57-c7ad-4cab-92ba-54e9d795d087" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_71d2abdf-fd6d-4023-b0ff-a13794acc893" xlink:to="loc_us-gaap_Goodwill_4cffbf57-c7ad-4cab-92ba-54e9d795d087" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_79d4d6f3-78f2-43e6-bc85-4793238e9641" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_162f3ca7-f1a7-455f-bb34-5b1d551e617b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_79d4d6f3-78f2-43e6-bc85-4793238e9641" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_162f3ca7-f1a7-455f-bb34-5b1d551e617b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_558bed87-6aac-4832-8aae-c8c18ed3dcee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_79d4d6f3-78f2-43e6-bc85-4793238e9641" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_558bed87-6aac-4832-8aae-c8c18ed3dcee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_ed971865-27ae-476f-a1ef-bd2e3b3c5803" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_79d4d6f3-78f2-43e6-bc85-4793238e9641" xlink:to="loc_us-gaap_LiabilitiesCurrent_ed971865-27ae-476f-a1ef-bd2e3b3c5803" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_293ca514-68bc-4b73-afb5-3ecd659a5cf7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_79d4d6f3-78f2-43e6-bc85-4793238e9641" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_293ca514-68bc-4b73-afb5-3ecd659a5cf7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_3cec70c1-1982-4814-90ff-5d7b4739f3dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_79d4d6f3-78f2-43e6-bc85-4793238e9641" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_3cec70c1-1982-4814-90ff-5d7b4739f3dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_43edf304-df3e-4348-8243-1e3ea395035e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_ea228860-2195-4387-a56b-863a1b08c6cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_43edf304-df3e-4348-8243-1e3ea395035e" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_ea228860-2195-4387-a56b-863a1b08c6cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_f3d2baa6-9168-49a2-a273-0f18498462be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_43edf304-df3e-4348-8243-1e3ea395035e" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_f3d2baa6-9168-49a2-a273-0f18498462be" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_86a5a8f6-638d-4f9b-8ebd-aed08e29cc34" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_43edf304-df3e-4348-8243-1e3ea395035e" xlink:to="loc_us-gaap_PreferredStockValue_86a5a8f6-638d-4f9b-8ebd-aed08e29cc34" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_d5ff2c77-0a71-4560-a510-43584d10f68e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_43edf304-df3e-4348-8243-1e3ea395035e" xlink:to="loc_us-gaap_AdditionalPaidInCapital_d5ff2c77-0a71-4560-a510-43584d10f68e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_7f980443-fd31-450e-9f15-3e3e14cfbd63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_43edf304-df3e-4348-8243-1e3ea395035e" xlink:to="loc_us-gaap_CommonStockValue_7f980443-fd31-450e-9f15-3e3e14cfbd63" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_0b297787-3985-4241-84a8-aa56e94a4b10" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_1b9fd1cf-e2d4-4125-8240-7b209812fb87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_0b297787-3985-4241-84a8-aa56e94a4b10" xlink:to="loc_us-gaap_Liabilities_1b9fd1cf-e2d4-4125-8240-7b209812fb87" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_bedb2b97-a011-46e9-a1cd-f9c019e4b406" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_0b297787-3985-4241-84a8-aa56e94a4b10" xlink:to="loc_us-gaap_CommitmentsAndContingencies_bedb2b97-a011-46e9-a1cd-f9c019e4b406" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_881c603c-c1b2-4ec4-856c-b1f7f4babc1e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_0b297787-3985-4241-84a8-aa56e94a4b10" xlink:to="loc_us-gaap_StockholdersEquity_881c603c-c1b2-4ec4-856c-b1f7f4babc1e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_e6690f23-f299-4f26-8d92-621cea06effa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_8d72251b-fe7d-4035-a098-c017e1b4b603" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_e6690f23-f299-4f26-8d92-621cea06effa" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_8d72251b-fe7d-4035-a098-c017e1b4b603" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_2ca3f168-ef32-4395-a371-760dc1aa57d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_e6690f23-f299-4f26-8d92-621cea06effa" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_2ca3f168-ef32-4395-a371-760dc1aa57d4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_eaac1956-2534-49b2-a159-7aa324d63ef7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_e6690f23-f299-4f26-8d92-621cea06effa" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_eaac1956-2534-49b2-a159-7aa324d63ef7" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="mgni-20230930.xsd#CondensedConsolidatedStatementsofOperations"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_4f12fa24-0fa4-4198-af7e-29648b649db1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_52dd8948-c311-4ae7-b243-9a0e18432b00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_4f12fa24-0fa4-4198-af7e-29648b649db1" xlink:to="loc_us-gaap_OperatingIncomeLoss_52dd8948-c311-4ae7-b243-9a0e18432b00" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_0852da0f-cbbb-4cb8-b0be-46010ea408ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_4f12fa24-0fa4-4198-af7e-29648b649db1" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_0852da0f-cbbb-4cb8-b0be-46010ea408ca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_d4230ba3-740c-462d-9d13-f21eea0caeb9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_19eda4a6-ac4a-4035-ad8d-4a4736aefe6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_d4230ba3-740c-462d-9d13-f21eea0caeb9" xlink:to="loc_us-gaap_SellingAndMarketingExpense_19eda4a6-ac4a-4035-ad8d-4a4736aefe6d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_dc9976d4-9bc3-4b9d-a7e8-bc6c8637d1b7" xlink:href="mgni-20230930.xsd#mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_d4230ba3-740c-462d-9d13-f21eea0caeb9" xlink:to="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_dc9976d4-9bc3-4b9d-a7e8-bc6c8637d1b7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_55b018f2-277a-4a3a-a6ec-daa10051a05f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_d4230ba3-740c-462d-9d13-f21eea0caeb9" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_55b018f2-277a-4a3a-a6ec-daa10051a05f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_3a3907d2-3544-4a01-b418-73708d22fe5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_d4230ba3-740c-462d-9d13-f21eea0caeb9" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_3a3907d2-3544-4a01-b418-73708d22fe5c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_c5f0802d-4202-4eae-82aa-3c65b8ce7bf4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_d4230ba3-740c-462d-9d13-f21eea0caeb9" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_c5f0802d-4202-4eae-82aa-3c65b8ce7bf4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_4cb52123-1b4d-48e1-806c-fcbde2e79fc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_25cd98f9-34b6-4da2-911f-9b171a521af7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_4cb52123-1b4d-48e1-806c-fcbde2e79fc4" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_25cd98f9-34b6-4da2-911f-9b171a521af7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_cc16af55-7972-4c78-ae8a-8fac988c3c06" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostsAndExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_4cb52123-1b4d-48e1-806c-fcbde2e79fc4" xlink:to="loc_us-gaap_CostsAndExpenses_cc16af55-7972-4c78-ae8a-8fac988c3c06" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_f7cdde3b-291f-496c-a26c-6b0558626fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_dbed2112-4949-48a0-acc5-500fc9e77c47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_f7cdde3b-291f-496c-a26c-6b0558626fb0" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_dbed2112-4949-48a0-acc5-500fc9e77c47" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_ce7d15d0-505f-49d8-a1e9-4bfe8d0f0ae7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_f7cdde3b-291f-496c-a26c-6b0558626fb0" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_ce7d15d0-505f-49d8-a1e9-4bfe8d0f0ae7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_de39caa2-d03e-4c7a-955e-dd0257b5050c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_f7cdde3b-291f-496c-a26c-6b0558626fb0" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_de39caa2-d03e-4c7a-955e-dd0257b5050c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncome_797b541c-b9f8-4b14-8f1f-ba5633431f10" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherOperatingIncome"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_f7cdde3b-291f-496c-a26c-6b0558626fb0" xlink:to="loc_us-gaap_OtherOperatingIncome_797b541c-b9f8-4b14-8f1f-ba5633431f10" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_77aedde4-0eda-45c7-8bb5-355deada473d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_3604e80c-5b3a-464a-993f-19c960198661" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_77aedde4-0eda-45c7-8bb5-355deada473d" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_3604e80c-5b3a-464a-993f-19c960198661" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_e99a70c4-b69d-4450-9f58-69560d5b50e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_77aedde4-0eda-45c7-8bb5-355deada473d" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_e99a70c4-b69d-4450-9f58-69560d5b50e8" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedStatementsofComprehensiveLoss" xlink:type="simple" xlink:href="mgni-20230930.xsd#CondensedConsolidatedStatementsofComprehensiveLoss"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/CondensedConsolidatedStatementsofComprehensiveLoss" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_b5a38bb8-b366-4abd-b4f6-512ed036cc55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_f0544445-b708-409d-a38e-2ee7c51b9c94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_b5a38bb8-b366-4abd-b4f6-512ed036cc55" xlink:to="loc_us-gaap_NetIncomeLoss_f0544445-b708-409d-a38e-2ee7c51b9c94" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_049ae9df-30f3-4687-a971-adb50f53c1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_b5a38bb8-b366-4abd-b4f6-512ed036cc55" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_049ae9df-30f3-4687-a971-adb50f53c1ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_e4c53450-b3fc-4c26-a1bc-d3e2075ab81e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_b814e1b9-0f3b-4a41-a0f0-3ece0c88da36" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_e4c53450-b3fc-4c26-a1bc-d3e2075ab81e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_b814e1b9-0f3b-4a41-a0f0-3ece0c88da36" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="mgni-20230930.xsd#CondensedConsolidatedStatementsofCashFlows"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_cd32c5d0-26f6-4cee-9020-85d46c5755fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_82138543-2177-477f-bdc8-c4c75142c52d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_cd32c5d0-26f6-4cee-9020-85d46c5755fe" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_82138543-2177-477f-bdc8-c4c75142c52d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_d65892c6-d6a5-4ea7-a4a7-393986c8fdc5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_cd32c5d0-26f6-4cee-9020-85d46c5755fe" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_d65892c6-d6a5-4ea7-a4a7-393986c8fdc5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToDevelopSoftware_875085b3-58ea-450d-8daa-cf0cc554fb9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToDevelopSoftware"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_cd32c5d0-26f6-4cee-9020-85d46c5755fe" xlink:to="loc_us-gaap_PaymentsToDevelopSoftware_875085b3-58ea-450d-8daa-cf0cc554fb9c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bda42101-1f06-45c8-bc22-7aa16d9f9a21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_5e3ab9ad-3576-4ae6-8f0d-cb3a0d0e669b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bda42101-1f06-45c8-bc22-7aa16d9f9a21" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_5e3ab9ad-3576-4ae6-8f0d-cb3a0d0e669b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashNoncurrent_ed77099b-0d2b-40d2-8ce9-a67501436772" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bda42101-1f06-45c8-bc22-7aa16d9f9a21" xlink:to="loc_us-gaap_RestrictedCashNoncurrent_ed77099b-0d2b-40d2-8ce9-a67501436772" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_0d1ec620-432c-43ff-a78f-9a9ea26091d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_bda42101-1f06-45c8-bc22-7aa16d9f9a21" xlink:to="loc_us-gaap_RestrictedCashCurrent_0d1ec620-432c-43ff-a78f-9a9ea26091d0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfConvertibleDebt_6f2a9268-65b1-49d6-8e2a-4ca1fbf44be0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfConvertibleDebt"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_RepaymentsOfConvertibleDebt_6f2a9268-65b1-49d6-8e2a-4ca1fbf44be0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_6c765311-4bd0-4893-acfb-d9043b11b8b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_6c765311-4bd0-4893-acfb-d9043b11b8b8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_98fc548e-27a3-49f8-8502-30b0ec2f581d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_RepaymentsOfDebt_98fc548e-27a3-49f8-8502-30b0ec2f581d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_5b65e8c7-246f-48bc-9907-f81c25b153dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_5b65e8c7-246f-48bc-9907-f81c25b153dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_36a42e7a-231f-4088-a9c4-9ff3c345f6b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_36a42e7a-231f-4088-a9c4-9ff3c345f6b9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_72707264-f532-402d-8446-8971033cc4ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_72707264-f532-402d-8446-8971033cc4ca" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_0ec792f3-4368-4e20-bc05-537297ce67d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_0ec792f3-4368-4e20-bc05-537297ce67d0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans_3f5bf109-fabc-47c0-acaf-b940d22f5928" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_83f3a09c-1f5d-4b75-b773-9349bda0d84c" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans_3f5bf109-fabc-47c0-acaf-b940d22f5928" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_536b2a45-44bc-47af-8e31-7449279769dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_536b2a45-44bc-47af-8e31-7449279769dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_ad934775-9e46-4125-8067-ae12e1f3ec25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_ad934775-9e46-4125-8067-ae12e1f3ec25" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_aba6349a-6ad9-4d87-b6ff-39292cafd28f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_aba6349a-6ad9-4d87-b6ff-39292cafd28f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_9212a34c-da36-4267-9dd4-f5ed69fb699d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_ShareBasedCompensation_9212a34c-da36-4267-9dd4-f5ed69fb699d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_58928733-c0a4-4e7e-b06c-e20843542291" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_58928733-c0a4-4e7e-b06c-e20843542291" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_467e29ca-edef-4282-94e7-9e1924d7f0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_467e29ca-edef-4282-94e7-9e1924d7f0c3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_e21455dc-783f-45b5-82b3-d80572908460" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_e21455dc-783f-45b5-82b3-d80572908460" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_2d048913-68c3-458c-a4c0-e08739fefd72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_2d048913-68c3-458c-a4c0-e08739fefd72" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_3f6aff4f-1c57-40ed-9870-7c4be518a0db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_3f6aff4f-1c57-40ed-9870-7c4be518a0db" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_NonCashLeaseExpense_29d965da-8ba8-4505-92a3-4b2daa4314de" xlink:href="mgni-20230930.xsd#mgni_NonCashLeaseExpense"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_mgni_NonCashLeaseExpense_29d965da-8ba8-4505-92a3-4b2daa4314de" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_4ef66fdb-f2cd-4d86-87d7-7cfee0906627" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_4ef66fdb-f2cd-4d86-87d7-7cfee0906627" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_1b51b521-49c6-4c71-b619-f5039aa8a6e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_1b51b521-49c6-4c71-b619-f5039aa8a6e3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_43ea8860-a51c-4ed6-97fc-dc4d71b7030c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_43ea8860-a51c-4ed6-97fc-dc4d71b7030c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_c5b3f439-5a22-4767-8ee2-ba9a75167d02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="14" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_c5b3f439-5a22-4767-8ee2-ba9a75167d02" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_e8f7115c-174a-4514-8eca-b8a91089ec5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_e8f7115c-174a-4514-8eca-b8a91089ec5a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_08515243-b174-481b-bd78-eff68b34cdd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_4610333a-fb63-4bc8-959a-513aa3e18c38" xlink:to="loc_us-gaap_NetIncomeLoss_08515243-b174-481b-bd78-eff68b34cdd9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_5426b524-b4df-486c-bf3e-40f758f460cd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_dcc98f67-7c51-4dd7-897d-7ca836410307" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_5426b524-b4df-486c-bf3e-40f758f460cd" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_dcc98f67-7c51-4dd7-897d-7ca836410307" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_149b345b-0359-440c-b660-1fee3e2c82cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_5426b524-b4df-486c-bf3e-40f758f460cd" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_149b345b-0359-440c-b660-1fee3e2c82cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_5d2d0693-dfbd-4b94-9b29-88b1a6f29c65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_5426b524-b4df-486c-bf3e-40f758f460cd" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_5d2d0693-dfbd-4b94-9b29-88b1a6f29c65" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7e4242fa-d150-4f15-996c-477f91115e1a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_5426b524-b4df-486c-bf3e-40f758f460cd" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_7e4242fa-d150-4f15-996c-477f91115e1a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/OtherBalanceSheetAmountsAccountsPayableandAccruedExpensesDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#OtherBalanceSheetAmountsAccountsPayableandAccruedExpensesDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/OtherBalanceSheetAmountsAccountsPayableandAccruedExpensesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_2ee1749e-557d-4487-ad90-564954c60e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AccountsPayableSellerCurrent_bf8b502b-ba41-486e-b4d7-552563edda59" xlink:href="mgni-20230930.xsd#mgni_AccountsPayableSellerCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_2ee1749e-557d-4487-ad90-564954c60e8d" xlink:to="loc_mgni_AccountsPayableSellerCurrent_bf8b502b-ba41-486e-b4d7-552563edda59" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableTradeCurrent_b6fe9c0c-fe7e-4614-891e-d50b83173650" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountsPayableTradeCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_2ee1749e-557d-4487-ad90-564954c60e8d" xlink:to="loc_us-gaap_AccountsPayableTradeCurrent_b6fe9c0c-fe7e-4614-891e-d50b83173650" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_2cd7100b-e599-45a4-85c5-5c388dda029d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_2ee1749e-557d-4487-ad90-564954c60e8d" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_2cd7100b-e599-45a4-85c5-5c388dda029d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_IndemnificationClaimAccrualCurrent_b9cced22-1161-4b0e-868c-d1a1adc72c97" xlink:href="mgni-20230930.xsd#mgni_IndemnificationClaimAccrualCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_2ee1749e-557d-4487-ad90-564954c60e8d" xlink:to="loc_mgni_IndemnificationClaimAccrualCurrent_b9cced22-1161-4b0e-868c-d1a1adc72c97" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/GoodwillIntangibleAssetsandInternalUseSoftwareDevelopmentCostsFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#GoodwillIntangibleAssetsandInternalUseSoftwareDevelopmentCostsFiniteLivedIntangibleAssetsDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/GoodwillIntangibleAssetsandInternalUseSoftwareDevelopmentCostsFiniteLivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ad0b7567-66e0-446b-81ca-784ad47cd77d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_9b81eefc-e064-464d-b59b-42efd341b610" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ad0b7567-66e0-446b-81ca-784ad47cd77d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_9b81eefc-e064-464d-b59b-42efd341b610" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_b248fc97-cc86-4420-91ca-b138c557bdec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_ad0b7567-66e0-446b-81ca-784ad47cd77d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_b248fc97-cc86-4420-91ca-b138c557bdec" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/GoodwillIntangibleAssetsandInternalUseSoftwareDevelopmentCostsFiniteLivedIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#GoodwillIntangibleAssetsandInternalUseSoftwareDevelopmentCostsFiniteLivedIntangibleAssetsFutureAmortizationExpenseDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/GoodwillIntangibleAssetsandInternalUseSoftwareDevelopmentCostsFiniteLivedIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_07a740fe-8f85-46f9-8cb4-a294ddee46df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_2be5db0d-541e-4cd4-9580-0c2004eb3102" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_07a740fe-8f85-46f9-8cb4-a294ddee46df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_2be5db0d-541e-4cd4-9580-0c2004eb3102" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_9f211ac7-c2c4-4b29-8c95-bcc0fb9eb24c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_07a740fe-8f85-46f9-8cb4-a294ddee46df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_9f211ac7-c2c4-4b29-8c95-bcc0fb9eb24c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_ee15c0ac-6641-4897-b2ac-2cbf70fc87f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_07a740fe-8f85-46f9-8cb4-a294ddee46df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_ee15c0ac-6641-4897-b2ac-2cbf70fc87f1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_8c90fa8c-c707-4899-9628-6340204006dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_07a740fe-8f85-46f9-8cb4-a294ddee46df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_8c90fa8c-c707-4899-9628-6340204006dc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_7ea680c8-2b20-4480-b727-3219b3e5fa84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_07a740fe-8f85-46f9-8cb4-a294ddee46df" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_7ea680c8-2b20-4480-b727-3219b3e5fa84" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/MergerAcquisitionandRestructuringCostsMergerandRestructuringCostActivityDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#MergerAcquisitionandRestructuringCostsMergerandRestructuringCostActivityDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/MergerAcquisitionandRestructuringCostsMergerandRestructuringCostActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:href="mgni-20230930.xsd#mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringReserveAndMergerRelatedCostsSettledWithoutCash_bd34a38c-08f0-4d23-a96b-d197cd693df0" xlink:href="mgni-20230930.xsd#mgni_RestructuringReserveAndMergerRelatedCostsSettledWithoutCash"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:to="loc_mgni_RestructuringReserveAndMergerRelatedCostsSettledWithoutCash_bd34a38c-08f0-4d23-a96b-d197cd693df0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringChargesMergerAndAcquisitionAssumedLossContracts_2579c252-0bc0-4c7f-910c-d7dd9464c83f" xlink:href="mgni-20230930.xsd#mgni_RestructuringChargesMergerAndAcquisitionAssumedLossContracts"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:to="loc_mgni_RestructuringChargesMergerAndAcquisitionAssumedLossContracts_2579c252-0bc0-4c7f-910c-d7dd9464c83f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringImpairmentsSettledWithoutCash_2c8ad1eb-35e1-44fe-8646-da2637a8586b" xlink:href="mgni-20230930.xsd#mgni_RestructuringImpairmentsSettledWithoutCash"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:to="loc_mgni_RestructuringImpairmentsSettledWithoutCash_2c8ad1eb-35e1-44fe-8646-da2637a8586b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_9a958741-220e-4fa9-93de-8fc0393c3648" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:to="loc_us-gaap_RestructuringCharges_9a958741-220e-4fa9-93de-8fc0393c3648" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringImpairmentCosts_7ef7b9da-68a1-4b7d-b873-a1c374aa6076" xlink:href="mgni-20230930.xsd#mgni_RestructuringImpairmentCosts"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:to="loc_mgni_RestructuringImpairmentCosts_7ef7b9da-68a1-4b7d-b873-a1c374aa6076" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_925d2785-ff66-415b-a9e3-8992eb96eee7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_979e9599-3041-42e9-82dc-995ad933ec1b" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_925d2785-ff66-415b-a9e3-8992eb96eee7" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_4a49c3d3-7c84-4bcd-a3f6-bd9a063302b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_4a49c3d3-7c84-4bcd-a3f6-bd9a063302b1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_9572604d-5589-4f53-84df-d88b73ae9e79" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_9572604d-5589-4f53-84df-d88b73ae9e79" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_53d896f5-b607-4396-943f-e0d04049411b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_53d896f5-b607-4396-943f-e0d04049411b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_db9012f4-a794-4dca-a07c-5a90271cc079" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_db9012f4-a794-4dca-a07c-5a90271cc079" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_d910164f-595e-4b88-b1ad-29355f53d19f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_d910164f-595e-4b88-b1ad-29355f53d19f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour_ebf07479-8695-43c5-a49b-2d3bc6f1d615" xlink:href="mgni-20230930.xsd#mgni_LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3ae094c9-0f37-4ca4-b1d3-cbe498d3f990" xlink:to="loc_mgni_LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour_ebf07479-8695-43c5-a49b-2d3bc6f1d615" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails_1" xlink:type="simple" xlink:href="mgni-20230930.xsd#LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails_1"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3dc0febd-034f-4a86-b415-377c56545604" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_20aea667-f8b3-4566-b593-dfe21b2ca945" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3dc0febd-034f-4a86-b415-377c56545604" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_20aea667-f8b3-4566-b593-dfe21b2ca945" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_a5fd266e-40ca-45cb-a1e0-7b9b3089b91a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3dc0febd-034f-4a86-b415-377c56545604" xlink:to="loc_us-gaap_OperatingLeaseLiability_a5fd266e-40ca-45cb-a1e0-7b9b3089b91a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CommitmentsandContingenciesContractualObligationsDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#CommitmentsandContingenciesContractualObligationsDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/CommitmentsandContingenciesContractualObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligation_8a291767-69fc-479d-b9fb-d675b4fab688" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractualObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear_37aa97ac-4c07-4f80-87fc-0517db790162" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_8a291767-69fc-479d-b9fb-d675b4fab688" xlink:to="loc_us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear_37aa97ac-4c07-4f80-87fc-0517db790162" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInSecondYear_b58fc059-d504-4820-8123-0c0144ff58fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractualObligationDueInSecondYear"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_8a291767-69fc-479d-b9fb-d675b4fab688" xlink:to="loc_us-gaap_ContractualObligationDueInSecondYear_b58fc059-d504-4820-8123-0c0144ff58fc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInNextTwelveMonths_296686e6-f99d-40fb-b4b0-1d08c3f1f762" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractualObligationDueInNextTwelveMonths"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_8a291767-69fc-479d-b9fb-d675b4fab688" xlink:to="loc_us-gaap_ContractualObligationDueInNextTwelveMonths_296686e6-f99d-40fb-b4b0-1d08c3f1f762" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtScheduleofLongtermDebtDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#DebtScheduleofLongtermDebtDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/DebtScheduleofLongtermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_54e03b71-f43c-433b-8c78-bf7c6182edd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_5b732e8e-3ccd-4ceb-abaf-e6b709f9367e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_54e03b71-f43c-433b-8c78-bf7c6182edd9" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_5b732e8e-3ccd-4ceb-abaf-e6b709f9367e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_032ad5a1-fd96-4cf6-91f7-3b6eeec8c429" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_54e03b71-f43c-433b-8c78-bf7c6182edd9" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_032ad5a1-fd96-4cf6-91f7-3b6eeec8c429" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtMaturitiesofPrincipleAmountofLongTermDebtDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#DebtMaturitiesofPrincipleAmountofLongTermDebtDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/DebtMaturitiesofPrincipleAmountofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_fb13eafe-671b-4c46-bb4f-c5adfc231df7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_fb13eafe-671b-4c46-bb4f-c5adfc231df7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_9278c789-977b-4e11-b5e2-1c3fde6bdc31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_9278c789-977b-4e11-b5e2-1c3fde6bdc31" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_8b00b26d-2d5c-4ab8-9463-b2db489ffe3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_8b00b26d-2d5c-4ab8-9463-b2db489ffe3e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_60b4eb26-c5e4-4952-89c6-90c33a64b863" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_60b4eb26-c5e4-4952-89c6-90c33a64b863" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear_ef86ae29-dda9-43c9-b5e0-5282bda4c6b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear_ef86ae29-dda9-43c9-b5e0-5282bda4c6b8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_5697b58c-a71c-4346-96b5-c9641aaf96bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebt_7c98beca-b753-4044-b1ff-28f0b4b34a71" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_5697b58c-a71c-4346-96b5-c9641aaf96bb" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtSummaryofTermLoanBFacilityDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#DebtSummaryofTermLoanBFacilityDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/DebtSummaryofTermLoanBFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_50d7a701-4948-47fa-b535-54bb975c1f41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_6de29de6-0558-4b1e-86ea-9d6769990124" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtNoncurrent_50d7a701-4948-47fa-b535-54bb975c1f41" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_6de29de6-0558-4b1e-86ea-9d6769990124" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_7bab04f9-6ff3-4c64-b054-c5a3d018c836" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtNoncurrent_50d7a701-4948-47fa-b535-54bb975c1f41" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_7bab04f9-6ff3-4c64-b054-c5a3d018c836" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_7c5dff64-29b1-4521-98f4-7d0eccaf049d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_LongTermDebtNoncurrent_50d7a701-4948-47fa-b535-54bb975c1f41" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_7c5dff64-29b1-4521-98f4-7d0eccaf049d" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtInterestExpenseRelatedtotheTermLoanBFacilityDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#DebtInterestExpenseRelatedtotheTermLoanBFacilityDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/DebtInterestExpenseRelatedtotheTermLoanBFacilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_d5d4e05b-9774-43cb-a804-c366ff925a49" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_a61f0019-ce96-4ac4-aacc-d5368d392a10" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_d5d4e05b-9774-43cb-a804-c366ff925a49" xlink:to="loc_us-gaap_InterestExpenseDebt_a61f0019-ce96-4ac4-aacc-d5368d392a10" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_44cc81c8-c6b1-42e6-8ad0-857cea34314b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfDebtDiscountPremium"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_d5d4e05b-9774-43cb-a804-c366ff925a49" xlink:to="loc_us-gaap_AmortizationOfDebtDiscountPremium_44cc81c8-c6b1-42e6-8ad0-857cea34314b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_3d8dc9d0-3c0b-4e3b-a330-813c231dcfef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfFinancingCosts"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_InterestExpense_d5d4e05b-9774-43cb-a804-c366ff925a49" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_3d8dc9d0-3c0b-4e3b-a330-813c231dcfef" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtAmortizationExpensefortheTermLoanBFacilityDebtDiscountandIssuanceCostsDetails" xlink:type="simple" xlink:href="mgni-20230930.xsd#DebtAmortizationExpensefortheTermLoanBFacilityDebtDiscountandIssuanceCostsDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/DebtAmortizationExpensefortheTermLoanBFacilityDebtDiscountandIssuanceCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearFive_876d0d14-d667-4426-bfb9-7172a7a2d54b" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtIssuanceCostsYearFive"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearFive_876d0d14-d667-4426-bfb9-7172a7a2d54b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearOne_47c5885d-b4ff-47f4-ab4e-08c7e3118418" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtIssuanceCostsYearOne"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearOne_47c5885d-b4ff-47f4-ab4e-08c7e3118418" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsRemainderOfFiscalYear_8105e093-109d-4e42-b83f-4a1a012d4226" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtIssuanceCostsRemainderOfFiscalYear"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsRemainderOfFiscalYear_8105e093-109d-4e42-b83f-4a1a012d4226" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearFour_6208186f-3d84-4b7e-9f3e-455dfbd599fe" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtIssuanceCostsYearFour"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearFour_6208186f-3d84-4b7e-9f3e-455dfbd599fe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearThree_b96d266a-8790-47d4-90de-cefaadddd0d3" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtIssuanceCostsYearThree"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearThree_b96d266a-8790-47d4-90de-cefaadddd0d3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearTwo_8a1267a9-ea4b-44f7-9ee5-be9489b8d787" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtIssuanceCostsYearTwo"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DeferredFinanceCostsNet_f08edd31-c6af-4e32-b1a5-f2dc26ca2852" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearTwo_8a1267a9-ea4b-44f7-9ee5-be9489b8d787" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearThree_0b7de391-9d70-48b9-aa08-e09d25a5f55c" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtDiscountPremiumYearThree"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearThree_0b7de391-9d70-48b9-aa08-e09d25a5f55c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearFour_f43cc42a-79be-4fd6-ba18-82c288feeead" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtDiscountPremiumYearFour"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearFour_f43cc42a-79be-4fd6-ba18-82c288feeead" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear_fc6fcc66-0bd9-4603-ab8c-8841d7b8a8d6" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear_fc6fcc66-0bd9-4603-ab8c-8841d7b8a8d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearOne_6829b2d4-61d9-4a13-8eaf-dba401cb3845" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtDiscountPremiumYearOne"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearOne_6829b2d4-61d9-4a13-8eaf-dba401cb3845" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearTwo_b70d0221-2876-4816-8099-b10a6c4ce25b" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtDiscountPremiumYearTwo"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearTwo_b70d0221-2876-4816-8099-b10a6c4ce25b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearFive_86d7f2a9-d1a3-4812-9260-9b660588f8a6" xlink:href="mgni-20230930.xsd#mgni_AmortizationOfDebtDiscountPremiumYearFive"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_1a0177a9-be8e-4b6b-8287-23766198fdc4" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearFive_86d7f2a9-d1a3-4812-9260-9b660588f8a6" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
