<?xml version="1.0" encoding="utf-8"?>
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <!-- INTEGIX by Ez-XBRL -->
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#ConsolidatedStatementsOfFinancialPosition" roleURI="http://www.metallaroyalty.com/role/ConsolidatedStatementsOfFinancialPosition"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#ConsolidatedStatementsOfLossAndComprehensiveLoss" roleURI="http://www.metallaroyalty.com/role/ConsolidatedStatementsOfLossAndComprehensiveLoss"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#ConsolidatedStatementsOfCashFlows" roleURI="http://www.metallaroyalty.com/role/ConsolidatedStatementsOfCashFlows"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#Scheduleofdetailedinformationabouttradeandotherreceivablesdetails" roleURI="http://www.metallaroyalty.com/role/Scheduleofdetailedinformationabouttradeandotherreceivablesdetails"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#GENERALANDADMINISTRATIVEEXPENSESDetails" roleURI="http://www.metallaroyalty.com/role/GENERALANDADMINISTRATIVEEXPENSESDetails"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#ScheduleOfDeferredIncomeTaxAssetLiabilityDetails" roleURI="http://www.metallaroyalty.com/role/ScheduleOfDeferredIncomeTaxAssetLiabilityDetails"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#ScheduleOfTransactionsBetweenRelatedPartiesDetails" roleURI="http://www.metallaroyalty.com/role/ScheduleOfTransactionsBetweenRelatedPartiesDetails"/>
  <roleRef xlink:type="simple" xlink:href="mta-20251231.xsd#ScheduleOfDetailedInformationAboutClassificationOfFinancialInstrumentsDetails" roleURI="http://www.metallaroyalty.com/role/ScheduleOfDetailedInformationAboutClassificationOfFinancialInstrumentsDetails"/>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/ConsolidatedStatementsOfFinancialPosition">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Assets" xlink:label="loc_ifrs-full_Assets_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentAssets" xlink:label="loc_ifrs-full_CurrentAssets_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashAndCashEquivalents" xlink:label="loc_ifrs-full_CashAndCashEquivalents_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentReceivables" xlink:label="loc_ifrs-full_TradeAndOtherCurrentReceivables_2"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentPrepaidExpenses" xlink:label="loc_ifrs-full_CurrentPrepaidExpenses_3"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentAssets" xlink:label="loc_ifrs-full_NoncurrentAssets_5"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_RoyaltyAndStreamInterests" xlink:label="loc_mta_RoyaltyAndStreamInterests_5"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxAssets" xlink:label="loc_ifrs-full_DeferredTaxAssets_6"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_InvestmentAccountedForUsingEquityMethod" xlink:label="loc_ifrs-full_InvestmentAccountedForUsingEquityMethod_7"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EquityAndLiabilities" xlink:label="loc_ifrs-full_EquityAndLiabilities_9"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Liabilities" xlink:label="loc_ifrs-full_Liabilities_10"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentLiabilities" xlink:label="loc_ifrs-full_CurrentLiabilities_10"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ShorttermBorrowings" xlink:label="loc_ifrs-full_ShorttermBorrowings_10"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_CurrentLiabilitiesOtherThanLoans" xlink:label="loc_mta_CurrentLiabilitiesOtherThanLoans_11"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentPayables" xlink:label="loc_ifrs-full_TradeAndOtherCurrentPayables_11"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherCurrentPayables" xlink:label="loc_ifrs-full_OtherCurrentPayables_12"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_NoncurrentLiabilities" xlink:label="loc_ifrs-full_NoncurrentLiabilities_15"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxLiabilities" xlink:label="loc_ifrs-full_DeferredTaxLiabilities_15"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_LongtermBorrowings" xlink:label="loc_ifrs-full_LongtermBorrowings_16"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherNoncurrentPayables" xlink:label="loc_ifrs-full_OtherNoncurrentPayables_17"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Equity" xlink:label="loc_ifrs-full_Equity_20"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IssuedCapital" xlink:label="loc_ifrs-full_IssuedCapital_20"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherReserves" xlink:label="loc_ifrs-full_OtherReserves_21"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RetainedEarnings" xlink:label="loc_ifrs-full_RetainedEarnings_22"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Assets_0" xlink:to="loc_ifrs-full_CurrentAssets_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CurrentAssets_1" xlink:to="loc_ifrs-full_CashAndCashEquivalents_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CurrentAssets_1" xlink:to="loc_ifrs-full_TradeAndOtherCurrentReceivables_2" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CurrentAssets_1" xlink:to="loc_ifrs-full_CurrentPrepaidExpenses_3" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Assets_0" xlink:to="loc_ifrs-full_NoncurrentAssets_5" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_NoncurrentAssets_5" xlink:to="loc_mta_RoyaltyAndStreamInterests_5" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_NoncurrentAssets_5" xlink:to="loc_ifrs-full_DeferredTaxAssets_6" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_NoncurrentAssets_5" xlink:to="loc_ifrs-full_InvestmentAccountedForUsingEquityMethod_7" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_EquityAndLiabilities_9" xlink:to="loc_ifrs-full_Liabilities_10" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Liabilities_10" xlink:to="loc_ifrs-full_CurrentLiabilities_10" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CurrentLiabilities_10" xlink:to="loc_ifrs-full_ShorttermBorrowings_10" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CurrentLiabilities_10" xlink:to="loc_mta_CurrentLiabilitiesOtherThanLoans_11" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_CurrentLiabilitiesOtherThanLoans_11" xlink:to="loc_ifrs-full_TradeAndOtherCurrentPayables_11" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_CurrentLiabilitiesOtherThanLoans_11" xlink:to="loc_ifrs-full_OtherCurrentPayables_12" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Liabilities_10" xlink:to="loc_ifrs-full_NoncurrentLiabilities_15" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_NoncurrentLiabilities_15" xlink:to="loc_ifrs-full_DeferredTaxLiabilities_15" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_NoncurrentLiabilities_15" xlink:to="loc_ifrs-full_LongtermBorrowings_16" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_NoncurrentLiabilities_15" xlink:to="loc_ifrs-full_OtherNoncurrentPayables_17" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_EquityAndLiabilities_9" xlink:to="loc_ifrs-full_Equity_20" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Equity_20" xlink:to="loc_ifrs-full_IssuedCapital_20" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Equity_20" xlink:to="loc_ifrs-full_OtherReserves_21" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_Equity_20" xlink:to="loc_ifrs-full_RetainedEarnings_22" order="20" use="optional" weight="1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/ConsolidatedStatementsOfLossAndComprehensiveLoss">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLoss" xlink:label="loc_ifrs-full_ProfitLoss_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossBeforeTax" xlink:label="loc_ifrs-full_ProfitLossBeforeTax_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLossFromOperatingActivities" xlink:label="loc_ifrs-full_ProfitLossFromOperatingActivities_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ExpenseFromSharebasedPaymentTransactionsWithEmployees" xlink:label="loc_ifrs-full_ExpenseFromSharebasedPaymentTransactionsWithEmployees_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeneralAndAdministrativeExpense" xlink:label="loc_ifrs-full_GeneralAndAdministrativeExpense_2"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GrossProfit" xlink:label="loc_ifrs-full_GrossProfit_3"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Revenue" xlink:label="loc_ifrs-full_Revenue_3"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_DepletionOnRoyaltyInterests" xlink:label="loc_mta_DepletionOnRoyaltyInterests_4"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss" xlink:label="loc_ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss_7"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherOperatingIncomeExpense" xlink:label="loc_ifrs-full_OtherOperatingIncomeExpense_8"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives" xlink:label="loc_ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives_9"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ShareOfProfitLossOfAssociatesAccountedForUsingEquityMethod" xlink:label="loc_ifrs-full_ShareOfProfitLossOfAssociatesAccountedForUsingEquityMethod_10"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_InterestExpense" xlink:label="loc_ifrs-full_InterestExpense_11"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinanceCosts" xlink:label="loc_ifrs-full_FinanceCosts_12"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GainsLossesOnRemeasuringAvailableforsaleFinancialAssetsBeforeTax" xlink:label="loc_ifrs-full_GainsLossesOnRemeasuringAvailableforsaleFinancialAssetsBeforeTax_13"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_GainLossOnModificationOfLoanPayable" xlink:label="loc_mta_GainLossOnModificationOfLoanPayable_14"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_GainOnSalesOfMineralClaims" xlink:label="loc_mta_GainOnSalesOfMineralClaims_15"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_GainLossesOnChangesInFairValueOfDerivativeLoanLiability" xlink:label="loc_mta_GainLossesOnChangesInFairValueOfDerivativeLoanLiability_16"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid" xlink:label="loc_ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid_17"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentTaxExpenseIncome" xlink:label="loc_ifrs-full_CurrentTaxExpenseIncome_19"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxExpenseIncome" xlink:label="loc_ifrs-full_DeferredTaxExpenseIncome_20"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLoss_0" xlink:to="loc_ifrs-full_ProfitLossBeforeTax_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_ProfitLossFromOperatingActivities_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossFromOperatingActivities_1" xlink:to="loc_ifrs-full_ExpenseFromSharebasedPaymentTransactionsWithEmployees_1" order="0" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossFromOperatingActivities_1" xlink:to="loc_ifrs-full_GeneralAndAdministrativeExpense_2" order="10" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossFromOperatingActivities_1" xlink:to="loc_ifrs-full_GrossProfit_3" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_GrossProfit_3" xlink:to="loc_ifrs-full_Revenue_3" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_GrossProfit_3" xlink:to="loc_mta_DepletionOnRoyaltyInterests_4" order="10" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_GainsLossesOnExchangeDifferencesOnTranslationRecognisedInProfitOrLoss_7" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_OtherOperatingIncomeExpense_8" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives_9" order="30" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_ShareOfProfitLossOfAssociatesAccountedForUsingEquityMethod_10" order="40" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_InterestExpense_11" order="50" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_FinanceCosts_12" order="60" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_GainsLossesOnRemeasuringAvailableforsaleFinancialAssetsBeforeTax_13" order="70" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_mta_GainLossOnModificationOfLoanPayable_14" order="80" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_mta_GainOnSalesOfMineralClaims_15" order="90" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_mta_GainLossesOnChangesInFairValueOfDerivativeLoanLiability_16" order="100" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLossBeforeTax_1" xlink:to="loc_ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid_17" order="110" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLoss_0" xlink:to="loc_ifrs-full_CurrentTaxExpenseIncome_19" order="10" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_ProfitLoss_0" xlink:to="loc_ifrs-full_DeferredTaxExpenseIncome_20" order="20" use="optional" weight="-1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/ConsolidatedStatementsOfCashFlows">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncreaseDecreaseInCashAndCashEquivalents" xlink:label="loc_ifrs-full_IncreaseDecreaseInCashAndCashEquivalents_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashFlowsFromUsedInOperatingActivities" xlink:label="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_AdjustmentsOfItemsNotAffectingCash" xlink:label="loc_mta_AdjustmentsOfItemsNotAffectingCash_1"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_DepletionOnRoyaltyInterests" xlink:label="loc_mta_DepletionOnRoyaltyInterests_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForInterestExpense" xlink:label="loc_ifrs-full_AdjustmentsForInterestExpense_2"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForFinanceCosts" xlink:label="loc_ifrs-full_AdjustmentsForFinanceCosts_3"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_GainOnSalesOfMineralClaims" xlink:label="loc_mta_GainOnSalesOfMineralClaims_4"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForUnrealisedForeignExchangeLossesGains" xlink:label="loc_ifrs-full_AdjustmentsForUnrealisedForeignExchangeLossesGains_5"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_GainLossesOnChangesInFairValueOfDerivativeLoanLiability" xlink:label="loc_mta_GainLossesOnChangesInFairValueOfDerivativeLoanLiability_6"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfitLoss" xlink:label="loc_ifrs-full_ProfitLoss_7"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid" xlink:label="loc_ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid_8"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForUndistributedProfitsOfInvestmentsAccountedForUsingEquityMethod" xlink:label="loc_ifrs-full_AdjustmentsForUndistributedProfitsOfInvestmentsAccountedForUsingEquityMethod_9"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_GainLossOnModificationOfLoanPayable" xlink:label="loc_mta_GainLossOnModificationOfLoanPayable_10"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives" xlink:label="loc_ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives_11"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForIncreaseDecreaseInEmployeeBenefitLiabilities" xlink:label="loc_ifrs-full_AdjustmentsForIncreaseDecreaseInEmployeeBenefitLiabilities_12"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherInflowsOutflowsOfCashClassifiedAsOperatingActivities" xlink:label="loc_ifrs-full_OtherInflowsOutflowsOfCashClassifiedAsOperatingActivities_13"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForIncomeTaxExpense" xlink:label="loc_ifrs-full_AdjustmentsForIncomeTaxExpense_14"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_PaymentsReceivedFromDerivativeRoyaltyAsset" xlink:label="loc_mta_PaymentsReceivedFromDerivativeRoyaltyAsset_16"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_IncomeTaxesPaidRefundClassifiedAsOperatingActivities" xlink:label="loc_ifrs-full_IncomeTaxesPaidRefundClassifiedAsOperatingActivities_17"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_IncreaseDecreasePrepaidExpensesAndOther" xlink:label="loc_mta_IncreaseDecreasePrepaidExpensesAndOther_18"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForDecreaseIncreaseInTradeAccountReceivable" xlink:label="loc_ifrs-full_AdjustmentsForDecreaseIncreaseInTradeAccountReceivable_19"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdjustmentsForIncreaseDecreaseInTradeAccountPayable" xlink:label="loc_ifrs-full_AdjustmentsForIncreaseDecreaseInTradeAccountPayable_20"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashFlowsFromUsedInInvestingActivities" xlink:label="loc_ifrs-full_CashFlowsFromUsedInInvestingActivities_22"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_CashFlowsUsedForAcquisitionsOfRoyaltyAndStreamInterests" xlink:label="loc_mta_CashFlowsUsedForAcquisitionsOfRoyaltyAndStreamInterests_22"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_ProceedsFromSaleOfMineralClaims" xlink:label="loc_mta_ProceedsFromSaleOfMineralClaims_23"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DividendsReceivedFromAssociatesClassifiedAsInvestingActivities" xlink:label="loc_ifrs-full_DividendsReceivedFromAssociatesClassifiedAsInvestingActivities_24"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CashFlowsFromUsedInFinancingActivities" xlink:label="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProceedsFromBorrowingsClassifiedAsFinancingActivities" xlink:label="loc_ifrs-full_ProceedsFromBorrowingsClassifiedAsFinancingActivities_26"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_RepaymentsOfBorrowingsClassifiedAsFinancingActivities" xlink:label="loc_ifrs-full_RepaymentsOfBorrowingsClassifiedAsFinancingActivities_27"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_ProceedsFromPrivatePlacement" xlink:label="loc_mta_ProceedsFromPrivatePlacement_28"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_ProceedsFromBeedieSubscription" xlink:label="loc_mta_ProceedsFromBeedieSubscription_29"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_ProceedsFromAtMarketNetOfShareIssueCosts" xlink:label="loc_mta_ProceedsFromAtMarketNetOfShareIssueCosts_30"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProceedsFromExerciseOfOptions" xlink:label="loc_ifrs-full_ProceedsFromExerciseOfOptions_31"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_RepaymentsOfFinanceChargesPaid" xlink:label="loc_mta_RepaymentsOfFinanceChargesPaid_32"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_InterestPaidClassifiedAsFinancingActivities" xlink:label="loc_ifrs-full_InterestPaidClassifiedAsFinancingActivities_33"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_EffectOfExchangeRateChangesOnCashAndCashEquivalents" xlink:label="loc_ifrs-full_EffectOfExchangeRateChangesOnCashAndCashEquivalents_35"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_IncreaseDecreaseInCashAndCashEquivalents_0" xlink:to="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" xlink:to="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_mta_DepletionOnRoyaltyInterests_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_AdjustmentsForInterestExpense_2" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_AdjustmentsForFinanceCosts_3" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_mta_GainOnSalesOfMineralClaims_4" order="30" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_AdjustmentsForUnrealisedForeignExchangeLossesGains_5" order="40" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_mta_GainLossesOnChangesInFairValueOfDerivativeLoanLiability_6" order="50" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_ProfitLoss_7" order="60" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_GainLossArisingFromDifferenceBetweenCarryingAmountOfFinancialLiabilityExtinguishedAndConsiderationPaid_8" order="70" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_AdjustmentsForUndistributedProfitsOfInvestmentsAccountedForUsingEquityMethod_9" order="80" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_mta_GainLossOnModificationOfLoanPayable_10" order="90" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_GainsLossesOnChangeInFairValueOfDerivatives_11" order="100" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_AdjustmentsForIncreaseDecreaseInEmployeeBenefitLiabilities_12" order="110" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_OtherInflowsOutflowsOfCashClassifiedAsOperatingActivities_13" order="120" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_mta_AdjustmentsOfItemsNotAffectingCash_1" xlink:to="loc_ifrs-full_AdjustmentsForIncomeTaxExpense_14" order="130" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" xlink:to="loc_mta_PaymentsReceivedFromDerivativeRoyaltyAsset_16" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" xlink:to="loc_ifrs-full_IncomeTaxesPaidRefundClassifiedAsOperatingActivities_17" order="20" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" xlink:to="loc_mta_IncreaseDecreasePrepaidExpensesAndOther_18" order="30" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" xlink:to="loc_ifrs-full_AdjustmentsForDecreaseIncreaseInTradeAccountReceivable_19" order="40" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInOperatingActivities_1" xlink:to="loc_ifrs-full_AdjustmentsForIncreaseDecreaseInTradeAccountPayable_20" order="50" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_IncreaseDecreaseInCashAndCashEquivalents_0" xlink:to="loc_ifrs-full_CashFlowsFromUsedInInvestingActivities_22" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInInvestingActivities_22" xlink:to="loc_mta_CashFlowsUsedForAcquisitionsOfRoyaltyAndStreamInterests_22" order="0" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInInvestingActivities_22" xlink:to="loc_mta_ProceedsFromSaleOfMineralClaims_23" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInInvestingActivities_22" xlink:to="loc_ifrs-full_DividendsReceivedFromAssociatesClassifiedAsInvestingActivities_24" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_IncreaseDecreaseInCashAndCashEquivalents_0" xlink:to="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_ifrs-full_ProceedsFromBorrowingsClassifiedAsFinancingActivities_26" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_ifrs-full_RepaymentsOfBorrowingsClassifiedAsFinancingActivities_27" order="10" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_mta_ProceedsFromPrivatePlacement_28" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_mta_ProceedsFromBeedieSubscription_29" order="30" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_mta_ProceedsFromAtMarketNetOfShareIssueCosts_30" order="40" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_ifrs-full_ProceedsFromExerciseOfOptions_31" order="50" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_mta_RepaymentsOfFinanceChargesPaid_32" order="60" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_CashFlowsFromUsedInFinancingActivities_26" xlink:to="loc_ifrs-full_InterestPaidClassifiedAsFinancingActivities_33" order="70" use="optional" weight="-1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_IncreaseDecreaseInCashAndCashEquivalents_0" xlink:to="loc_ifrs-full_EffectOfExchangeRateChangesOnCashAndCashEquivalents_35" order="30" use="optional" weight="1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/Scheduleofdetailedinformationabouttradeandotherreceivablesdetails">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentReceivables" xlink:label="loc_ifrs-full_TradeAndOtherCurrentReceivables_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentTradeReceivables" xlink:label="loc_ifrs-full_CurrentTradeReceivables_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentReceivablesFromTaxesOtherThanIncomeTax" xlink:label="loc_ifrs-full_CurrentReceivablesFromTaxesOtherThanIncomeTax_2"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherCurrentReceivables" xlink:label="loc_ifrs-full_OtherCurrentReceivables_3"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_TradeAndOtherCurrentReceivables_0" xlink:to="loc_ifrs-full_CurrentTradeReceivables_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_TradeAndOtherCurrentReceivables_0" xlink:to="loc_ifrs-full_CurrentReceivablesFromTaxesOtherThanIncomeTax_2" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_TradeAndOtherCurrentReceivables_0" xlink:to="loc_ifrs-full_OtherCurrentReceivables_3" order="20" use="optional" weight="1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/GENERALANDADMINISTRATIVEEXPENSESDetails">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_GeneralAndAdministrativeExpense" xlink:label="loc_ifrs-full_GeneralAndAdministrativeExpense_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_WagesAndSalaries" xlink:label="loc_ifrs-full_WagesAndSalaries_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_AdministrativeExpense" xlink:label="loc_ifrs-full_AdministrativeExpense_2"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_ListingAndFilingFees" xlink:label="loc_mta_ListingAndFilingFees_3"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_ProfessionalFeesExpense" xlink:label="loc_ifrs-full_ProfessionalFeesExpense_4"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_GeneralAndAdministrativeExpense_0" xlink:to="loc_ifrs-full_WagesAndSalaries_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_GeneralAndAdministrativeExpense_0" xlink:to="loc_ifrs-full_AdministrativeExpense_2" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_GeneralAndAdministrativeExpense_0" xlink:to="loc_mta_ListingAndFilingFees_3" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_GeneralAndAdministrativeExpense_0" xlink:to="loc_ifrs-full_ProfessionalFeesExpense_4" order="30" use="optional" weight="1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/ScheduleOfDeferredIncomeTaxAssetLiabilityDetails">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeferredTaxLiabilityAsset" xlink:label="loc_ifrs-full_DeferredTaxLiabilityAsset_0"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_DeferredTaxLiabilities1" xlink:label="loc_mta_DeferredTaxLiabilities1_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised" xlink:label="loc_ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised_2"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_DeferredTaxAssets1" xlink:label="loc_mta_DeferredTaxAssets1_3"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_DeferredTaxLiabilityAsset_0" xlink:to="loc_mta_DeferredTaxLiabilities1_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_DeferredTaxLiabilityAsset_0" xlink:to="loc_ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised_2" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_DeferredTaxLiabilityAsset_0" xlink:to="loc_mta_DeferredTaxAssets1_3" order="20" use="optional" weight="-1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/ScheduleOfTransactionsBetweenRelatedPartiesDetails">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_KeyManagementPersonnelCompensation" xlink:label="loc_ifrs-full_KeyManagementPersonnelCompensation_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_KeyManagementPersonnelCompensationShorttermEmployeeBenefits" xlink:label="loc_ifrs-full_KeyManagementPersonnelCompensationShorttermEmployeeBenefits_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_KeyManagementPersonnelCompensationSharebasedPayment" xlink:label="loc_ifrs-full_KeyManagementPersonnelCompensationSharebasedPayment_2"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_KeyManagementPersonnelCompensation_0" xlink:to="loc_ifrs-full_KeyManagementPersonnelCompensationShorttermEmployeeBenefits_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_KeyManagementPersonnelCompensation_0" xlink:to="loc_ifrs-full_KeyManagementPersonnelCompensationSharebasedPayment_2" order="10" use="optional" weight="1"/>
  </calculationLink>
  <calculationLink xlink:type="extended" xlink:role="http://www.metallaroyalty.com/role/ScheduleOfDetailedInformationAboutClassificationOfFinancialInstrumentsDetails">
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialLiabilitiesAtAmortisedCost" xlink:label="loc_ifrs-full_FinancialLiabilitiesAtAmortisedCost_0"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_TradeAndOtherCurrentPayablesToTradeSuppliers" xlink:label="loc_ifrs-full_TradeAndOtherCurrentPayablesToTradeSuppliers_1"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_DerivativeFinancialLiabilities" xlink:label="loc_ifrs-full_DerivativeFinancialLiabilities_2"/>
    <loc xlink:type="locator" xlink:href="mta-20251231.xsd#mta_AcquisitionPayables" xlink:label="loc_mta_AcquisitionPayables_3"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Borrowings" xlink:label="loc_ifrs-full_Borrowings_4"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialAssetsAtFairValue" xlink:label="loc_ifrs-full_FinancialAssetsAtFairValue_5"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_CurrentTradeReceivables" xlink:label="loc_ifrs-full_CurrentTradeReceivables_6"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLoss" xlink:label="loc_ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLoss_7"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_Cash" xlink:label="loc_ifrs-full_Cash_8"/>
    <loc xlink:type="locator" xlink:href="https://xbrl.ifrs.org/taxonomy/2025-03-27/full_ifrs/full_ifrs-cor_2025-03-27.xsd#ifrs-full_OtherReceivables" xlink:label="loc_ifrs-full_OtherReceivables_9"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialLiabilitiesAtAmortisedCost_0" xlink:to="loc_ifrs-full_TradeAndOtherCurrentPayablesToTradeSuppliers_1" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialLiabilitiesAtAmortisedCost_0" xlink:to="loc_ifrs-full_DerivativeFinancialLiabilities_2" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialLiabilitiesAtAmortisedCost_0" xlink:to="loc_mta_AcquisitionPayables_3" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialLiabilitiesAtAmortisedCost_0" xlink:to="loc_ifrs-full_Borrowings_4" order="30" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialAssetsAtFairValue_5" xlink:to="loc_ifrs-full_CurrentTradeReceivables_6" order="0" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialAssetsAtFairValue_5" xlink:to="loc_ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLoss_7" order="10" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialAssetsAtFairValue_5" xlink:to="loc_ifrs-full_Cash_8" order="20" use="optional" weight="1"/>
    <calculationArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_ifrs-full_FinancialAssetsAtFairValue_5" xlink:to="loc_ifrs-full_OtherReceivables_9" order="30" use="optional" weight="1"/>
  </calculationLink>
</linkbase>