Convert both offers into one currency using a current rate, then include card or bank conversion fees, shipping, taxes, and any import charges shown at checkout. Check the exchange rate and fee your payment provider will actually use; a public converter is only a starting estimate.
Match the exact product variant and seller terms. Returns, warranty support, and return shipping can outweigh a small apparent currency advantage. Record the rate's timestamp if the purchase is not immediate, because it may change before payment.
Compare the final amount payable, not two isolated sticker prices.
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