The Hidden Cost of Changing Money
The rate you see online is not the rate you get. Where the margin is added, what each method typically costs, and the one question to always answer "no".
Currency conversion is unusual among financial products in that the fee is often not stated as a fee. It is built into the exchange rate, where it is invisible unless you know what to compare against.
The mid-market rate
When you search for an exchange rate, you get the mid-market rate — the midpoint between what banks are buying and selling a currency for on the wholesale market. It is the rate quoted by search engines, financial news and most conversion tools.
Nobody offers it to consumers. It is the reference point, not a price.
The difference between the mid-market rate and the rate you are actually given is the spread, and it is where the cost lives. A provider advertising "0% commission" may still be taking 4% in the spread, and the claim is technically true.
To find what you are really paying: divide the amount you received by the amount you handed over, and compare that rate to the mid-market rate. The gap, as a percentage, is your actual cost.
What each method typically costs
Ranges, because providers vary a great deal:
| Method | Typical total cost |
|---|---|
| Specialist transfer services | 0.3–1% |
| Cards with no foreign transaction fee | 0–1% |
| Major bank card abroad | 2.75–3% plus spread |
| High-street bank cash exchange | 3–5% |
| Airport bureau de change | 5–12% |
| Dynamic currency conversion | 3–12% on top |
The spread between the best and worst options is roughly tenfold. On a £2,000 holiday budget that is the difference between about £10 and about £150.
Always decline "pay in your own currency"
This is the single most expensive mistake, and it is presented as a convenience.
When you pay by card abroad, the terminal may ask whether you want to be charged in the local currency or your home currency. Choosing your home currency is dynamic currency conversion, and it means the merchant's payment processor does the conversion at a rate they set — typically 3–12% worse than the card network's.
The offer is designed to feel safer. It shows you a familiar number, so you know exactly what you are paying. What it does not show is that the same purchase in local currency would have cost less.
Always choose the local currency. Your card network — Visa or Mastercard — will convert at close to the mid-market rate, and your bank's foreign transaction fee, if any, applies on top. That combination is essentially always cheaper than DCC.
The same question appears at foreign ATMs ("with conversion" or "without conversion") and on some online checkouts. Same answer: local currency, every time.
The other things that add up
Foreign transaction fees. Most standard bank cards charge 2.75–3% on any transaction in a foreign currency — including online purchases from foreign websites, which people often do not realise are affected. Several banks and app-based accounts charge nothing.
ATM fees, on both ends. Your bank may charge a withdrawal fee, and the ATM operator may charge its own on top. Making one large withdrawal instead of four small ones avoids repeating the fixed portion.
Weekend margins. Currency markets close at the weekend. Some providers widen their spread on Saturday and Sunday to cover the risk of Monday's opening rate. If a transfer is not urgent, weekdays are cheaper.
Credit card cash advances. Withdrawing cash on a credit card usually triggers a cash advance fee and interest from the day of withdrawal, with no grace period. This is one of the most expensive ways to obtain foreign currency.
Airport exchange. Convenience priced accordingly. The margin is highest of anywhere, because at that point the customer has no alternative — which is precisely why it is priced that way.
A reasonable approach
- Get a card with no foreign transaction fees before travelling. This is the single highest-value step and takes minutes.
- Pay by card where cards are accepted, always choosing local currency.
- Withdraw cash once or twice in reasonable amounts rather than repeatedly in small ones.
- Do not exchange cash at the airport except for a small amount if you genuinely need some on arrival.
- For larger transfers, compare specialist services against your bank. On a few thousand pounds the difference is usually large enough to be worth ten minutes.
- Keep some local cash. Card acceptance varies more than travel advice suggests, particularly for taxis, markets and small rural businesses.
Checking a rate
The currency converter uses mid-market rates, which makes it useful as the benchmark rather than as a quote: convert the amount you are about to exchange, then compare against what you are actually being offered. The gap is what the transaction costs you.
For working out that gap as a percentage, the percentage calculator handles it directly — and it is worth doing once for whatever method you habitually use, because most people have never checked and are surprised by the answer.