How to Use This Tool
Most currency converters answer a question nobody is actually asking. They tell you what 100 euros is worth at the mid-market rate — the wholesale rate banks trade with each other at, which no consumer has ever been given. The number that lands on your statement is different, and it is different by an amount most people never bother to calculate. This tool calculates it.
Step one: enter the purchase
Type the amount exactly as the merchant quoted it, and pick the currency they quoted it in. Then choose the currency your card is billed in — that is your home currency, not the currency of the country you happen to be standing in. The greyed-out figure on the right is the mid-market conversion: correct, and optimistic.
Step two: set your two fees
There are two separate charges and almost every converter online ignores both. The first is your issuer's foreign transaction fee, a flat percentage your bank adds for the privilege of a non-domestic transaction. It is usually between 0% and 3%, it is printed in your card's summary box, and some travel cards genuinely charge nothing. Use the preset buttons if you know your card type, or type the exact figure.
The second is the network conversion margin. Visa and Mastercard each publish a daily rate used to convert the transaction, and that rate is deliberately set slightly worse than mid-market. It typically costs another 0.5% to 1%. Nobody itemises it on a statement, which is precisely why it is worth modelling here.
Step three: read the four figures
The large number is what you will be billed. Beneath it, four boxes break the result apart: the honest mid-market conversion, the total fees added in cash terms, your effective exchange rate once everything is included, and the cost per 100 units of spending. That last figure is the useful one for comparing cards, because it stays constant regardless of purchase size and makes a 3% card and a 0% card impossible to confuse.
Getting a better number
- Always decline dynamic currency conversion. If a terminal offers to charge you in your home currency, it is applying its own markup — frequently 4% to 7% — on top of everything above. Choose the local currency every time.
- Compare on effective rate, not headline fee. A card advertising "no foreign fees" that uses a poor internal rate can cost more than a 1% card on a good rate.
- Watch small transactions. Where a fixed minimum fee applies, a 4 euro coffee can carry a double-digit percentage cost.