The displayed headline rate and the actual credited amount are not necessarily the same calculation. A provider can charge a separate fee or incorporate its charge into the offered rate.
Calculate the full effective rate
Conversion uses an exchange rate and may add a spread or explicit fee. The effective rate is the amount actually received divided by the original amount paid, using a consistent direction. A displayed market rate is not necessarily the rate a card issuer, wallet or operator applies to the transaction.
Suppose a fictional conversion changes 100 currency units at ₹80 per unit, then deducts a ₹200 fee. The gross amount is ₹8,000 and the net credit is ₹7,800. The effective net rate is ₹78 per original unit. Comparing only the ₹80 headline overlooks the fee.
More than one conversion can occur
A bank account, payment wallet and platform balance can each use different currencies. A transaction may therefore be converted twice. At withdrawal, the reverse rate can also differ from the deposit rate. Receiving less does not automatically mean a missing credit; the route and applied rates must be reconciled.
Records that explain the difference
Save the source amount, source currency, destination amount, destination currency, timestamp, applied rate and each fee. Distinguish a fee charged separately from one deducted from the received balance. Rate movements affect comparisons across dates, so avoid treating two differently timed transactions as identical. A favourable conversion quote is not a guarantee of the final amount unless the provider's terms lock it for the relevant transaction.
In practice
Converting 10 hypothetical units at ₹80 per unit gives ₹800 before any separate fee. A ₹20 fee deducted afterwards would leave ₹780.
What to check
Record the source currency, destination currency, applied rate and fees. Compare final credited amounts on the same basis instead of comparing rates alone.