There is no single expensive mistake in handling money abroad. There are five moderately expensive ones, each taking a few percent, and a traveller who makes all of them on a two-week trip can lose the price of a decent dinner every day without noticing.
1. Dynamic currency conversion — the big one
You pay by card in Spain and the terminal asks: would you like to be charged in euros or in your home currency? Your home currency sounds helpful and reassuring. It is the single most expensive button in travel.
Choosing your home currency hands the conversion to the merchant's payment processor, which sets its own rate and typically takes 3 to 6 percent above the interbank rate. Choosing the local currency hands it to your card network, which uses something close to the interbank rate.
Always choose the local currency. Always. In every country, on every terminal, at every ATM. There is no situation in which paying in your home currency abroad is cheaper, and the offer is designed to look like the safe option precisely because it is not.
2. Your card's own foreign transaction fee
Separate from the above and charged by your own bank — commonly 2 to 3 percent on every foreign purchase. Many travel-oriented and digital-first cards charge nothing.
This is worth fixing once. Getting a single no-foreign-fee card before a long trip pays for the effort within the first week and then keeps paying for years. Check the fee on your existing cards; people are frequently wrong about which of theirs is free.
3. The ATM's surcharge
Two separate charges can apply at a foreign ATM: your bank's fee, and the machine operator's own surcharge, which is disclosed on screen and easy to click past.
The worst offenders are the standalone machines in tourist areas and airports — brands not attached to a bank. Bank-operated ATMs inside or beside a branch are generally cheaper. And because the fee is often a flat amount, fewer, larger withdrawals cost less than many small ones.
The ATM will also offer you dynamic currency conversion. Decline it there too — this is where it is most often accepted by accident.
4. Airport exchange counters
The spread at an airport bureau de change is routinely 8 to 12 percent, and "0% commission" signage refers only to the absent commission, not to the rate, which is where the money is taken.
If you need arrival cash, take it from a bank ATM in the terminal, or bring a small amount from home and change the rest properly later.
5. The ship, and other closed economies
A cruise ship, a resort and an airline are closed economies with no competition inside them. Onboard accounts are usually denominated in dollars or euros regardless of where the ship is sailing, and any conversion applied is at the operator's rate.
The specific thing to check: if your onboard account is in a currency other than your card's, you are converting once at the end of the cruise on the whole balance. Setting the account to your own currency is occasionally offered and is occasionally worse — it depends on whether the line or your bank is doing the conversion. Ask which rate applies.
What actually to carry
- Two cards from different networks, kept in different places. A Visa and a Mastercard. Card networks have regional outages and machines have preferences; a second card is the cheapest travel insurance there is.
- At least one card with no foreign transaction fee.
- A modest amount of local cash — for taxis, small cafés, tips and the places where the terminal is broken. Southern Europe is more cash-dependent than northern Europe.
- A note of your bank's international phone number, which is not the number on the back of the card if you cannot use the card.
- Travel notifications set, if your bank still requires them.
Two habits worth forming
Check the currency on the terminal before you tap. It takes two seconds and it is where the three to six percent lives.
Keep one card untouched in the safe. The most common financial emergency abroad is not fraud, it is a card retained by a machine or blocked by an over-eager fraud algorithm on a Sunday. A second card in a second place turns a crisis into an inconvenience.
The short version
- Always pay in the local currency. Dynamic currency conversion costs 3–6%.
- Get one card with no foreign transaction fee. That is another 2–3%.
- Use bank ATMs, not standalone ones, and withdraw larger amounts less often.
- Airport exchange counters cost 8–12%. Use an ATM instead.
- Carry two cards on different networks, in different places, and keep one in the safe.