Currency conversion margin calculator — reveal the hidden markup
When you exchange money or send an international transfer, the exchange rate you are offered is almost never the real mid-market rate. The difference — the margin — is a hidden cost that is easy to miss because it is folded into the rate rather than shown as a fee. This calculator turns that margin into a clear percentage and a cash amount so you can compare providers honestly.
How it works
The margin is (mid-market rate − quoted rate) ÷ mid-market rate × 100. To turn it
into money, the tool converts your amount at both rates and takes the difference,
then adds any fixed fee (expressed in the target currency at the mid-market rate).
The total cost as a percentage tells you what share of your money the provider
keeps.
Worked example
You want to send 1,000 of your home currency. The mid-market rate is 1.1700 and your app quotes 1.1350 with no fixed fee.
- At mid-market:
1,000 × 1.1700 = 1,170.00 - At the quoted rate:
1,000 × 1.1350 = 1,135.00 - Hidden cost:
1,170.00 − 1,135.00 = 35.00(about 2.99% of the amount)
Even with “no fees”, the wide rate margin costs 35 units of the target currency.
Practical tips
Always compare on total cost. A provider advertising a low fixed fee but a wide rate margin can be more expensive than one charging a fee with a tight rate. Enter both into this tool to compare like for like.
Card payments abroad. The same margin idea applies to spending on a card overseas. Compare the rate your card applied against the mid-market rate for that day to see the markup.
Larger amounts magnify the margin. Because the margin is a percentage, doubling the transfer roughly doubles the hidden cost — worth shopping around for on big transfers.
All calculations run entirely in your browser — nothing is uploaded or stored.