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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:f5abaec5-98eb-4bc8-9127-53b5821fcd65,g:2b7a5230-f1a8-43e2-87aa-42134573e717-->
<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-20240630.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_LiabilitiesAndStockholdersEquity_20147e8c-6c1b-4c88-a509-45af4c0dd76e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_ebe708de-fed8-4ee8-80e6-6d2b4a133534" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_20147e8c-6c1b-4c88-a509-45af4c0dd76e" xlink:to="loc_us-gaap_Liabilities_ebe708de-fed8-4ee8-80e6-6d2b4a133534" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_9287f293-3535-408a-99c2-230fa0129a07" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_20147e8c-6c1b-4c88-a509-45af4c0dd76e" xlink:to="loc_us-gaap_CommitmentsAndContingencies_9287f293-3535-408a-99c2-230fa0129a07" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_1f9fb9f0-764f-49aa-ba9d-bf4241b3f8a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_20147e8c-6c1b-4c88-a509-45af4c0dd76e" xlink:to="loc_us-gaap_StockholdersEquity_1f9fb9f0-764f-49aa-ba9d-bf4241b3f8a8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_0ec5d3dd-665c-485e-ab4a-2a49749291d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_us-gaap_AssetsCurrent_0ec5d3dd-665c-485e-ab4a-2a49749291d5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_8c97f9db-8dba-4a5f-ab1c-995d9803dda0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_8c97f9db-8dba-4a5f-ab1c-995d9803dda0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_4b7aa321-20d1-422f-a5be-77d6b160e111" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_4b7aa321-20d1-422f-a5be-77d6b160e111" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_InternalUseSoftwareDevelopmentCostsNet_71bae2aa-87fc-4a8a-a912-2ffc9f4af6f6" xlink:href="mgni-20240630.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_mgni_InternalUseSoftwareDevelopmentCostsNet_71bae2aa-87fc-4a8a-a912-2ffc9f4af6f6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_84085158-1924-4ba4-8999-c061e45d1cab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_84085158-1924-4ba4-8999-c061e45d1cab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_1b271f7c-4779-4b34-a7e3-8e353303d29c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_1b271f7c-4779-4b34-a7e3-8e353303d29c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_3a2bc090-2eb5-4908-9939-e9134cf02f86" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_d132e854-f3ee-47e6-9d79-db9ab923f763" xlink:to="loc_us-gaap_Goodwill_3a2bc090-2eb5-4908-9939-e9134cf02f86" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_43b11c9f-6255-473a-8474-4ab696f679d9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_37b25084-7d25-4c54-a145-623b0f07d3b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_43b11c9f-6255-473a-8474-4ab696f679d9" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_37b25084-7d25-4c54-a145-623b0f07d3b3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_5dd3ad13-30ff-4b2a-b643-c45ad7ed90d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_43b11c9f-6255-473a-8474-4ab696f679d9" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_5dd3ad13-30ff-4b2a-b643-c45ad7ed90d1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_7dfefba9-f2cf-4b8b-b74c-bdd469b66c70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_43b11c9f-6255-473a-8474-4ab696f679d9" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_7dfefba9-f2cf-4b8b-b74c-bdd469b66c70" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_574ccae2-5d09-43ac-ab7a-239bf0efbe87" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_fdf98a9e-8a66-4287-aec9-e28678a772b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_574ccae2-5d09-43ac-ab7a-239bf0efbe87" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_fdf98a9e-8a66-4287-aec9-e28678a772b4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_1bc9aaab-b0e4-43ed-90e5-b3926c8e3f6f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_574ccae2-5d09-43ac-ab7a-239bf0efbe87" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_1bc9aaab-b0e4-43ed-90e5-b3926c8e3f6f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_58332e7d-9c5e-4bfa-b5ba-43b191b09a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_574ccae2-5d09-43ac-ab7a-239bf0efbe87" xlink:to="loc_us-gaap_PreferredStockValue_58332e7d-9c5e-4bfa-b5ba-43b191b09a2d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_5b91859f-5320-4637-b2af-0cc82406bc0e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_574ccae2-5d09-43ac-ab7a-239bf0efbe87" xlink:to="loc_us-gaap_AdditionalPaidInCapital_5b91859f-5320-4637-b2af-0cc82406bc0e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_caf465d9-37b0-434e-8997-ccd5ddcf72ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_574ccae2-5d09-43ac-ab7a-239bf0efbe87" xlink:to="loc_us-gaap_CommonStockValue_caf465d9-37b0-434e-8997-ccd5ddcf72ce" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_94172057-0072-43fa-b443-38923da488a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_5a4365d5-f2f6-413d-a7ae-89cf48ce85e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_94172057-0072-43fa-b443-38923da488a2" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_5a4365d5-f2f6-413d-a7ae-89cf48ce85e0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_cb7e5b1f-f5b8-4b2d-bf9c-aca8206c6cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_94172057-0072-43fa-b443-38923da488a2" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_cb7e5b1f-f5b8-4b2d-bf9c-aca8206c6cfe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_16c80b92-909a-458f-b67c-3be74c00179a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_94172057-0072-43fa-b443-38923da488a2" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_16c80b92-909a-458f-b67c-3be74c00179a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_bf7efe2d-25c8-4787-b1ce-f49118474186" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_94172057-0072-43fa-b443-38923da488a2" xlink:to="loc_us-gaap_LiabilitiesCurrent_bf7efe2d-25c8-4787-b1ce-f49118474186" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_42e2e03c-7f2b-4c1d-8aa1-2312d7732baa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_94172057-0072-43fa-b443-38923da488a2" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_42e2e03c-7f2b-4c1d-8aa1-2312d7732baa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_c4880f63-960f-4250-9413-a02ebbb19711" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_e6a3c266-8e12-4da5-b8ba-bb811d612f7a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c4880f63-960f-4250-9413-a02ebbb19711" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_e6a3c266-8e12-4da5-b8ba-bb811d612f7a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_9e33204a-c581-4ab2-8910-a6f07d1469a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c4880f63-960f-4250-9413-a02ebbb19711" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_9e33204a-c581-4ab2-8910-a6f07d1469a9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_c1747e72-527b-48fc-9463-5aaea4270fc1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c4880f63-960f-4250-9413-a02ebbb19711" xlink:to="loc_us-gaap_DebtCurrent_c1747e72-527b-48fc-9463-5aaea4270fc1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_53a95140-84fb-40ac-bd36-acea694eef8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c4880f63-960f-4250-9413-a02ebbb19711" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_53a95140-84fb-40ac-bd36-acea694eef8c" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="mgni-20240630.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_OperatingIncomeLoss_cd62c3fb-b1fa-4745-b9a1-07200cdb9544" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_4e56f3b1-5a1c-4386-abf3-1e48d352f861" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_cd62c3fb-b1fa-4745-b9a1-07200cdb9544" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_4e56f3b1-5a1c-4386-abf3-1e48d352f861" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_8abb6e39-58be-4223-a489-5f60fd4e91f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_cd62c3fb-b1fa-4745-b9a1-07200cdb9544" xlink:to="loc_us-gaap_CostsAndExpenses_8abb6e39-58be-4223-a489-5f60fd4e91f0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_ac2fe169-df7b-42fb-8e6c-e5e6973d483b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncome_e075fd1c-11dd-43da-bb21-f237361b96b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherOperatingIncome"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_ac2fe169-df7b-42fb-8e6c-e5e6973d483b" xlink:to="loc_us-gaap_OtherOperatingIncome_e075fd1c-11dd-43da-bb21-f237361b96b9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_f74b23bf-258b-48bb-ab00-bab188cb8cce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_ac2fe169-df7b-42fb-8e6c-e5e6973d483b" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_f74b23bf-258b-48bb-ab00-bab188cb8cce" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_67996763-e204-4151-996c-0342c539fa21" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_ac2fe169-df7b-42fb-8e6c-e5e6973d483b" xlink:to="loc_us-gaap_InterestExpenseNonoperating_67996763-e204-4151-996c-0342c539fa21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_21d494d2-53ef-468f-9031-906e61093424" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_ac2fe169-df7b-42fb-8e6c-e5e6973d483b" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_21d494d2-53ef-468f-9031-906e61093424" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_6a6c0be9-c6bb-4aab-88fb-07123b423023" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_dd34f0ec-9d70-44bc-977a-5e4d852eb09c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_6a6c0be9-c6bb-4aab-88fb-07123b423023" xlink:to="loc_us-gaap_OperatingIncomeLoss_dd34f0ec-9d70-44bc-977a-5e4d852eb09c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_aa4fb01e-57f5-4e21-a53c-3faa16326d58" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_6a6c0be9-c6bb-4aab-88fb-07123b423023" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_aa4fb01e-57f5-4e21-a53c-3faa16326d58" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_851bdd3b-37f1-40e6-975b-90d922f61f70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostsAndExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_ca38a7bb-49c6-4f0c-a06f-1a03499c426f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_851bdd3b-37f1-40e6-975b-90d922f61f70" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_ca38a7bb-49c6-4f0c-a06f-1a03499c426f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_8fd9ea96-a856-4c5c-bf93-15601ccea9a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_851bdd3b-37f1-40e6-975b-90d922f61f70" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_8fd9ea96-a856-4c5c-bf93-15601ccea9a8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_b299572d-10fc-4dac-bf7b-cce883839f18" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_851bdd3b-37f1-40e6-975b-90d922f61f70" xlink:to="loc_us-gaap_SellingAndMarketingExpense_b299572d-10fc-4dac-bf7b-cce883839f18" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_474f6954-47f4-48ad-b59d-886e906e1227" xlink:href="mgni-20240630.xsd#mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_851bdd3b-37f1-40e6-975b-90d922f61f70" xlink:to="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_474f6954-47f4-48ad-b59d-886e906e1227" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_94a3bc48-356e-4b45-98cf-8b0066dbf269" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_851bdd3b-37f1-40e6-975b-90d922f61f70" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_94a3bc48-356e-4b45-98cf-8b0066dbf269" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_8299558c-8eb2-4c3b-9547-2bc0a8e05e16" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2727bb17-6d87-414c-803f-7c3eff92b7b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8299558c-8eb2-4c3b-9547-2bc0a8e05e16" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2727bb17-6d87-414c-803f-7c3eff92b7b4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_39bff2fc-1b55-482f-b49a-d799de2f0ebd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8299558c-8eb2-4c3b-9547-2bc0a8e05e16" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_39bff2fc-1b55-482f-b49a-d799de2f0ebd" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedStatementsofComprehensiveLoss" xlink:type="simple" xlink:href="mgni-20240630.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_674894e7-2482-41ac-9f26-51627b6daf88" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_29950d24-fc3b-4b97-a79d-9cabba3d0544" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_674894e7-2482-41ac-9f26-51627b6daf88" xlink:to="loc_us-gaap_NetIncomeLoss_29950d24-fc3b-4b97-a79d-9cabba3d0544" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_27c43bd4-18fd-4219-ada5-61b5bc1bfde0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_674894e7-2482-41ac-9f26-51627b6daf88" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_27c43bd4-18fd-4219-ada5-61b5bc1bfde0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_5c248ec6-19e6-436d-b313-93ee6421fad9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_20f2d3d5-e443-49df-b6f0-c3fd0a69bb2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_5c248ec6-19e6-436d-b313-93ee6421fad9" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_20f2d3d5-e443-49df-b6f0-c3fd0a69bb2c" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CondensedConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="mgni-20240630.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_8700cd86-2838-47a1-b565-993af17422e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_105a32af-d249-433c-b8b3-ca90c705e2b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8700cd86-2838-47a1-b565-993af17422e1" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_105a32af-d249-433c-b8b3-ca90c705e2b2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToDevelopSoftware_2eec686f-6fcb-46c8-bf6f-2cb650f1decd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToDevelopSoftware"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_8700cd86-2838-47a1-b565-993af17422e1" xlink:to="loc_us-gaap_PaymentsToDevelopSoftware_2eec686f-6fcb-46c8-bf6f-2cb650f1decd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_027db010-edfc-4ea9-a3c8-6a52687e26b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_6b1ca86d-f690-4762-a44f-538809e422da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_027db010-edfc-4ea9-a3c8-6a52687e26b3" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_6b1ca86d-f690-4762-a44f-538809e422da" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_5a1e9715-e10d-4d7c-9f03-c09789d47dd3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_027db010-edfc-4ea9-a3c8-6a52687e26b3" xlink:to="loc_us-gaap_RestrictedCashCurrent_5a1e9715-e10d-4d7c-9f03-c09789d47dd3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_53fece7a-576e-48ac-84a3-9451922d3ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_8a698750-a782-4218-8491-5d7303bf22a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_53fece7a-576e-48ac-84a3-9451922d3ce8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_8a698750-a782-4218-8491-5d7303bf22a3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_3fe1e0f9-a3ca-45d9-bd7f-6fc6d2d61329" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_53fece7a-576e-48ac-84a3-9451922d3ce8" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_3fe1e0f9-a3ca-45d9-bd7f-6fc6d2d61329" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_37a6fc77-69d4-4863-9ab8-bb6cc070b4f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_53fece7a-576e-48ac-84a3-9451922d3ce8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_37a6fc77-69d4-4863-9ab8-bb6cc070b4f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b780a18f-cde6-4248-89c5-5614fd063f20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_53fece7a-576e-48ac-84a3-9451922d3ce8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_b780a18f-cde6-4248-89c5-5614fd063f20" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_889bf2d5-02a8-416a-8c98-24e3f380262b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_889bf2d5-02a8-416a-8c98-24e3f380262b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_a49f7697-7ef6-4625-bab0-b618a36c9f78" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_a49f7697-7ef6-4625-bab0-b618a36c9f78" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_24801929-8411-411e-9ff5-928252af148a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_ShareBasedCompensation_24801929-8411-411e-9ff5-928252af148a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_0086fdbd-06bd-4037-8d06-6ce13754229f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_0086fdbd-06bd-4037-8d06-6ce13754229f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_90bb90fc-12f8-436f-8429-6f2ec9297f82" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossOnSaleOfPropertyPlantEquipment"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_GainLossOnSaleOfPropertyPlantEquipment_90bb90fc-12f8-436f-8429-6f2ec9297f82" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_88b691b2-7534-453b-a14b-9c2ece7e9e5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_88b691b2-7534-453b-a14b-9c2ece7e9e5f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_2ac1d931-8951-48fd-8b2d-4cffc196fae5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_2ac1d931-8951-48fd-8b2d-4cffc196fae5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_0e353733-67fa-4da7-9d75-1b16f6a54e47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_0e353733-67fa-4da7-9d75-1b16f6a54e47" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_NonCashLeaseExpense_b15ad3f0-b00e-4a9f-887b-a1d733f457ef" xlink:href="mgni-20240630.xsd#mgni_NonCashLeaseExpense"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_mgni_NonCashLeaseExpense_b15ad3f0-b00e-4a9f-887b-a1d733f457ef" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_a1170921-c00e-4f82-a2f5-e5b2228a6a54" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyTransactionGainLossUnrealized"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossUnrealized_a1170921-c00e-4f82-a2f5-e5b2228a6a54" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_0c8f3faa-dbdb-46e1-a1a3-81e728a0880b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_0c8f3faa-dbdb-46e1-a1a3-81e728a0880b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_b3ba1d63-6e28-48c1-a5ea-aa027d860480" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_b3ba1d63-6e28-48c1-a5ea-aa027d860480" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_d27574e6-f15b-4f5f-ace3-7793e2581aa1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="13" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_d27574e6-f15b-4f5f-ace3-7793e2581aa1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_1eab13ee-395a-4dea-a278-58e72f03006c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_1eab13ee-395a-4dea-a278-58e72f03006c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_b90dbf9c-d5b9-4c9c-89b9-c457c5f8f7d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_37537c45-50de-49e6-a88b-a3f8293a9ce9" xlink:to="loc_us-gaap_NetIncomeLoss_b90dbf9c-d5b9-4c9c-89b9-c457c5f8f7d4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSecuredDebt_a3f73e7e-4887-4144-a752-73c6c72178d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfSecuredDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSecuredDebt_a3f73e7e-4887-4144-a752-73c6c72178d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_030e1bc7-d50d-4489-b1d7-d395b1955f27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_030e1bc7-d50d-4489-b1d7-d395b1955f27" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_7c7eb4c9-16f6-48f9-b99c-1637dff47a81" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_7c7eb4c9-16f6-48f9-b99c-1637dff47a81" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfSecuredDebt_d20d3cf2-23d5-4721-bd3e-efdaa11c1757" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfSecuredDebt"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_RepaymentsOfSecuredDebt_d20d3cf2-23d5-4721-bd3e-efdaa11c1757" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_b04e1427-12ba-4220-8157-fdda21533432" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_b04e1427-12ba-4220-8157-fdda21533432" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans_a9ec7139-b744-4af3-93e2-8e3f780f9976" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlans_a9ec7139-b744-4af3-93e2-8e3f780f9976" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_bbe8a7bd-acaf-4920-8df8-c0e70491910a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_bbe8a7bd-acaf-4920-8df8-c0e70491910a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfConvertibleDebt_c69bcf93-3506-4ffa-a7db-5c87961437fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfConvertibleDebt"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_RepaymentsOfConvertibleDebt_c69bcf93-3506-4ffa-a7db-5c87961437fe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_c1580df5-3edc-4c31-936f-cd3eafee8e20" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_a1753b88-8a7c-4d45-a3a4-b538a54ad10d" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_c1580df5-3edc-4c31-936f-cd3eafee8e20" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/OtherBalanceSheetAmountsDetails" xlink:type="simple" xlink:href="mgni-20240630.xsd#OtherBalanceSheetAmountsDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/OtherBalanceSheetAmountsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_9861fc28-d92a-4e53-b301-73910304786d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AccountsPayableSellerCurrent_bbc2bf20-e14c-4c58-b74b-475515097fd7" xlink:href="mgni-20240630.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_9861fc28-d92a-4e53-b301-73910304786d" xlink:to="loc_mgni_AccountsPayableSellerCurrent_bbc2bf20-e14c-4c58-b74b-475515097fd7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableTradeCurrent_f8f2fde3-30c8-46f7-b130-9d0b4385078f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_9861fc28-d92a-4e53-b301-73910304786d" xlink:to="loc_us-gaap_AccountsPayableTradeCurrent_f8f2fde3-30c8-46f7-b130-9d0b4385078f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_13be728f-274c-41cc-96b5-9228933c2907" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_9861fc28-d92a-4e53-b301-73910304786d" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_13be728f-274c-41cc-96b5-9228933c2907" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/PropertyandEquipmentSummaryofPropertyandEquipmentbyMajorClassDetails" xlink:type="simple" xlink:href="mgni-20240630.xsd#PropertyandEquipmentSummaryofPropertyandEquipmentbyMajorClassDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/PropertyandEquipmentSummaryofPropertyandEquipmentbyMajorClassDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_13441df3-91a9-4a34-9422-4a9c273267cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_3a45b1a3-6f8e-4269-a5aa-3cc5e62de05f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_13441df3-91a9-4a34-9422-4a9c273267cd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_3a45b1a3-6f8e-4269-a5aa-3cc5e62de05f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_2cbda12b-0e94-4d9a-b137-9e1bf1953801" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_13441df3-91a9-4a34-9422-4a9c273267cd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_2cbda12b-0e94-4d9a-b137-9e1bf1953801" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/IntangibleAssetsFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="mgni-20240630.xsd#IntangibleAssetsFiniteLivedIntangibleAssetsDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/IntangibleAssetsFiniteLivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_006c3bb4-20af-4250-a8c0-2f91cc8846e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_e2d0aa28-eeb4-412b-8395-510b8e74846c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_006c3bb4-20af-4250-a8c0-2f91cc8846e1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_e2d0aa28-eeb4-412b-8395-510b8e74846c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_3870b5ea-3044-4c3e-83c6-0af483fc034b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_006c3bb4-20af-4250-a8c0-2f91cc8846e1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_3870b5ea-3044-4c3e-83c6-0af483fc034b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/IntangibleAssetsFiniteLivedIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="simple" xlink:href="mgni-20240630.xsd#IntangibleAssetsFiniteLivedIntangibleAssetsFutureAmortizationExpenseDetails"/>
  <link:calculationLink xlink:role="http://www.magnite.com/role/IntangibleAssetsFiniteLivedIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_c9d33ac9-110e-4504-919e-abffd4b54b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_818c0fff-c5b2-42e7-9d27-18e9e219180f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c9d33ac9-110e-4504-919e-abffd4b54b6c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_818c0fff-c5b2-42e7-9d27-18e9e219180f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_ed83cf02-ec30-4222-8392-7fd0307a74eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c9d33ac9-110e-4504-919e-abffd4b54b6c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_ed83cf02-ec30-4222-8392-7fd0307a74eb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_6c9cbab5-b086-4968-a178-b40eb54c3e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c9d33ac9-110e-4504-919e-abffd4b54b6c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_6c9cbab5-b086-4968-a178-b40eb54c3e2c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_b825c158-2cf9-47de-b8a3-30b0d3999b80" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_c9d33ac9-110e-4504-919e-abffd4b54b6c" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_b825c158-2cf9-47de-b8a3-30b0d3999b80" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/MergerAcquisitionandRestructuringCostsMergerandRestructuringCostActivityDetails" xlink:type="simple" xlink:href="mgni-20240630.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_e47aae6c-f5cb-4d09-bd67-7681cd4f1d49" xlink:href="mgni-20240630.xsd#mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringReserveAndMergerRelatedCostsSettledWithoutCash_82b62212-872f-42bd-a656-463b3bf8d7d8" xlink:href="mgni-20240630.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_e47aae6c-f5cb-4d09-bd67-7681cd4f1d49" xlink:to="loc_mgni_RestructuringReserveAndMergerRelatedCostsSettledWithoutCash_82b62212-872f-42bd-a656-463b3bf8d7d8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringChargesMergerAndAcquisitionAssumedLossContracts_4b94ff09-3a3b-47f9-9b19-84d992b32002" xlink:href="mgni-20240630.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_e47aae6c-f5cb-4d09-bd67-7681cd4f1d49" xlink:to="loc_mgni_RestructuringChargesMergerAndAcquisitionAssumedLossContracts_4b94ff09-3a3b-47f9-9b19-84d992b32002" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_f80cd506-816f-4707-87cd-4cd4d6a4d25e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCharges"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_e47aae6c-f5cb-4d09-bd67-7681cd4f1d49" xlink:to="loc_us-gaap_RestructuringCharges_f80cd506-816f-4707-87cd-4cd4d6a4d25e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_RestructuringImpairmentCosts_abf40bd8-23ad-4c11-9e8f-3b9c870b9f79" xlink:href="mgni-20240630.xsd#mgni_RestructuringImpairmentCosts"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mgni_RestructuringChargesAndBusinessCombinationAcquisitionRelatedCosts_e47aae6c-f5cb-4d09-bd67-7681cd4f1d49" xlink:to="loc_mgni_RestructuringImpairmentCosts_abf40bd8-23ad-4c11-9e8f-3b9c870b9f79" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails" xlink:type="simple" xlink:href="mgni-20240630.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_eae8f2b4-efd0-4544-be88-9404cf4f0470" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_8c94cbad-18cc-492f-8874-712f36a7a1ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_eae8f2b4-efd0-4544-be88-9404cf4f0470" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_8c94cbad-18cc-492f-8874-712f36a7a1ce" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_9f863887-0f6d-48db-96ee-59407a8fd1de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_eae8f2b4-efd0-4544-be88-9404cf4f0470" xlink:to="loc_us-gaap_OperatingLeaseLiability_9f863887-0f6d-48db-96ee-59407a8fd1de" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/LeaseObligationsScheduleofLeaseLiabilityMaturitiesDetails_1" xlink:type="simple" xlink:href="mgni-20240630.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_386834e8-f65c-406b-b585-5945864d9c54" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_386834e8-f65c-406b-b585-5945864d9c54" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_18316230-046a-4fde-8878-a019687b0b97" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_18316230-046a-4fde-8878-a019687b0b97" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_cc219be0-07a4-42fb-b6ce-695461e9fb5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_cc219be0-07a4-42fb-b6ce-695461e9fb5d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_22b42f0a-8dfa-4bb7-ad79-71da48d60b84" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_22b42f0a-8dfa-4bb7-ad79-71da48d60b84" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_cab8c470-462b-40f6-a5f1-1018508dc4f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_cab8c470-462b-40f6-a5f1-1018508dc4f4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour_52533bd0-f883-4f14-a7f3-b609ce60862b" xlink:href="mgni-20240630.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_e57285e5-f70d-4e1d-8db1-6e8d7629247b" xlink:to="loc_mgni_LesseeOperatingLeaseLiabilityToBePaidDueAfterYearFour_52533bd0-f883-4f14-a7f3-b609ce60862b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/CommitmentsandContingenciesContractualObligationsDetails" xlink:type="simple" xlink:href="mgni-20240630.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_6801c73c-b8c8-4903-a123-dcbd6e65d16f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractualObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInSecondYear_b8562193-e92c-4362-b973-f50fe16cbb96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractualObligationDueInSecondYear"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_6801c73c-b8c8-4903-a123-dcbd6e65d16f" xlink:to="loc_us-gaap_ContractualObligationDueInSecondYear_b8562193-e92c-4362-b973-f50fe16cbb96" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInFourthYear_3b585307-733d-460b-b41c-470daddda836" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractualObligationDueInFourthYear"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_6801c73c-b8c8-4903-a123-dcbd6e65d16f" xlink:to="loc_us-gaap_ContractualObligationDueInFourthYear_3b585307-733d-460b-b41c-470daddda836" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear_839c562f-04d9-4652-b039-48eee1cd4fe9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_6801c73c-b8c8-4903-a123-dcbd6e65d16f" xlink:to="loc_us-gaap_ContractualObligationFutureMinimumPaymentsDueRemainderOfFiscalYear_839c562f-04d9-4652-b039-48eee1cd4fe9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInThirdYear_64cfd2a5-20b9-4030-a82e-c3726dd30897" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractualObligationDueInThirdYear"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_6801c73c-b8c8-4903-a123-dcbd6e65d16f" xlink:to="loc_us-gaap_ContractualObligationDueInThirdYear_64cfd2a5-20b9-4030-a82e-c3726dd30897" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractualObligationDueInNextTwelveMonths_67dbb422-8b69-4906-ab20-0476ca95ab92" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractualObligationDueInNextTwelveMonths"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_ContractualObligation_6801c73c-b8c8-4903-a123-dcbd6e65d16f" xlink:to="loc_us-gaap_ContractualObligationDueInNextTwelveMonths_67dbb422-8b69-4906-ab20-0476ca95ab92" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtScheduleofLongtermDebtDetails" xlink:type="simple" xlink:href="mgni-20240630.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_8ec218bc-ec47-4c2d-9c59-b2be4a69a614" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_3764fb19-5cea-41ca-975b-2c27bb05d9b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8ec218bc-ec47-4c2d-9c59-b2be4a69a614" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_3764fb19-5cea-41ca-975b-2c27bb05d9b4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_d15ada28-5844-4954-9487-a2b31c8c12d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_8ec218bc-ec47-4c2d-9c59-b2be4a69a614" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_d15ada28-5844-4954-9487-a2b31c8c12d4" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtMaturitiesofPrincipleAmountofLongTermDebtDetails" xlink:type="simple" xlink:href="mgni-20240630.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_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtLongtermAndShorttermCombinedAmount"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_e832b5c6-8ae0-4ade-8e93-965069fcd818" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_e832b5c6-8ae0-4ade-8e93-965069fcd818" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_c0648576-d964-45c4-9349-39b16224db28" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_c0648576-d964-45c4-9349-39b16224db28" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_b1b2eec4-f40f-4690-b21e-975d2412e5e6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_b1b2eec4-f40f-4690-b21e-975d2412e5e6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_bcf56d4c-0d8a-4f38-a112-1106db0f8705" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_bcf56d4c-0d8a-4f38-a112-1106db0f8705" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_5733b68a-494c-4de0-ae2e-e311ff3aec17" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_5733b68a-494c-4de0-ae2e-e311ff3aec17" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear_3f192a9d-f114-46f9-b363-29fb78bbcc9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtLongtermAndShorttermCombinedAmount_cb851544-02a9-4ef0-b1b4-21ebfbe13000" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear_3f192a9d-f114-46f9-b363-29fb78bbcc9a" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtSummaryofTermLoanBFacilityDetails" xlink:type="simple" xlink:href="mgni-20240630.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_73bff597-9b9b-4a4a-bd39-2853a09e5113" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_5fd34e68-5d5c-467d-8fe7-0b57fe63ba8b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_73bff597-9b9b-4a4a-bd39-2853a09e5113" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_5fd34e68-5d5c-467d-8fe7-0b57fe63ba8b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_d7062ce7-62d5-4a8f-9b9a-be791eaef0bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_73bff597-9b9b-4a4a-bd39-2853a09e5113" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_d7062ce7-62d5-4a8f-9b9a-be791eaef0bd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_321094d5-6354-417b-997f-7e7ae0ec678b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_73bff597-9b9b-4a4a-bd39-2853a09e5113" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_321094d5-6354-417b-997f-7e7ae0ec678b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtInterestExpenseRelatedtotheTermLoanBFacilityDetails" xlink:type="simple" xlink:href="mgni-20240630.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_0dfe01c9-c392-4bd9-b847-3cefcbed4f64" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_abe11996-1f6d-400e-9062-6b5691f3f923" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_0dfe01c9-c392-4bd9-b847-3cefcbed4f64" xlink:to="loc_us-gaap_InterestExpenseDebt_abe11996-1f6d-400e-9062-6b5691f3f923" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_0af5703d-4416-4450-8e55-64b6d04eb845" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_0dfe01c9-c392-4bd9-b847-3cefcbed4f64" xlink:to="loc_us-gaap_AmortizationOfDebtDiscountPremium_0af5703d-4416-4450-8e55-64b6d04eb845" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_5628399d-a1af-45b0-89f2-3125e8fd84f5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.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_0dfe01c9-c392-4bd9-b847-3cefcbed4f64" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_5628399d-a1af-45b0-89f2-3125e8fd84f5" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.magnite.com/role/DebtAmortizationExpensefortheTermLoanBFacilityDebtDiscountandIssuanceCostsDetails" xlink:type="simple" xlink:href="mgni-20240630.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_DebtInstrumentUnamortizedDiscount_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscount"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearFour_4112f28e-5c3f-41c5-a44a-78abf133f3f5" xlink:href="mgni-20240630.xsd#mgni_AmortizationOfDebtDiscountPremiumYearFour"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearFour_4112f28e-5c3f-41c5-a44a-78abf133f3f5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearOne_9498f9f9-4678-45ab-abfb-0e5a814c5b6e" xlink:href="mgni-20240630.xsd#mgni_AmortizationOfDebtDiscountPremiumYearOne"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearOne_9498f9f9-4678-45ab-abfb-0e5a814c5b6e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear_b7f4edf1-1c02-4092-be98-b8f8fb6730a2" xlink:href="mgni-20240630.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_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumRemainderOfFiscalYear_b7f4edf1-1c02-4092-be98-b8f8fb6730a2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearTwo_d66c5636-ffcf-4d2e-b3d6-b93f139ab8ac" xlink:href="mgni-20240630.xsd#mgni_AmortizationOfDebtDiscountPremiumYearTwo"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearTwo_d66c5636-ffcf-4d2e-b3d6-b93f139ab8ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearThree_3efc0baa-9423-4b55-8dce-a1829295c385" xlink:href="mgni-20240630.xsd#mgni_AmortizationOfDebtDiscountPremiumYearThree"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaap_DebtInstrumentUnamortizedDiscount_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearThree_3efc0baa-9423-4b55-8dce-a1829295c385" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtDiscountPremiumYearFive_4c04254f-5482-4d00-9324-6b98cfc1a238" xlink:href="mgni-20240630.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_d4615d9f-8a65-473a-acae-4594c387d7f3" xlink:to="loc_mgni_AmortizationOfDebtDiscountPremiumYearFive_4c04254f-5482-4d00-9324-6b98cfc1a238" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearFive_8d18c187-660c-40bf-b3b0-553d0c0452ea" xlink:href="mgni-20240630.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_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearFive_8d18c187-660c-40bf-b3b0-553d0c0452ea" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearOne_aab7a047-87de-472e-a871-d1cd021c8798" xlink:href="mgni-20240630.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_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearOne_aab7a047-87de-472e-a871-d1cd021c8798" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsRemainderOfFiscalYear_85427ebe-685b-4396-94c0-5c57402086d6" xlink:href="mgni-20240630.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_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsRemainderOfFiscalYear_85427ebe-685b-4396-94c0-5c57402086d6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearFour_7f760ac7-db1e-4ffc-b101-cc1f66780407" xlink:href="mgni-20240630.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_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearFour_7f760ac7-db1e-4ffc-b101-cc1f66780407" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearThree_8fb6a370-9f74-4afa-bce4-60e678362d98" xlink:href="mgni-20240630.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_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearThree_8fb6a370-9f74-4afa-bce4-60e678362d98" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_mgni_AmortizationOfDebtIssuanceCostsYearTwo_e01e83a3-eb40-4be7-8d41-5b42329cc4d3" xlink:href="mgni-20240630.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_a0173029-3f16-4b55-a6ec-b9e9c24447bc" xlink:to="loc_mgni_AmortizationOfDebtIssuanceCostsYearTwo_e01e83a3-eb40-4be7-8d41-5b42329cc4d3" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
