Seeing a price abroad and wondering "how much is that in my money?" is part of every trip. But currency conversion is more than multiplying by an exchange rate: which rate is used, your bank's fees and how you pay all change what you actually spend. This guide covers the basic calculation, how to work out the real cost and the most common mistakes.
Short answer: Multiply the foreign amount by the exchange rate that shows how much one unit of the foreign currency is worth in your currency. To find the real cost, add your bank's foreign transaction fee and any fixed charges. When paying by card, always choose the local currency, and build a small buffer into your budget for exchange rate changes.
Real cost calculator
Enter the foreign amount, the exchange rate and your bank's fee to see the estimated total you'll pay:
Fee: 2.93
Estimated total: 100.68 in your currency
Effective rate you pay: 1 unit ≈ 1.18
The values in the calculator are examples only and don't reflect current rates. For your own calculation, use the current rate from your bank or a trusted source and the fee from your bank's fee schedule.
1. How basic conversion works
Exchange rates are usually shown as "1 unit of foreign currency = X of your currency". So:
- Foreign currency to your currency: foreign amount × rate. If 1 EUR = 1.15 USD, a €85 dinner costs 85 × 1.15 = $97.75.
- Your currency to foreign currency: your amount ÷ rate. At the same rate, a $1,000 budget is 1,000 ÷ 1.15 ≈ €870.
(The rates in these examples are illustrative values chosen to show the calculation.)
A practical shortcut on the go: round the rate to an easy number and multiply in your head. It won't be exact, but you'll instantly know whether a price is expensive or reasonable.
2. Which rate? Buy, sell and mid-market
The single rate you see on screen may actually sit between several different rates:
- Mid-market rate: The rate shown on news sites and currency apps. It's the midpoint between buy and sell rates and usually isn't what you're charged.
- Sell rate: The rate at which a bank or exchange office sells you foreign currency. It's higher than the mid-market rate.
- Buy rate: The rate at which they buy foreign currency back from you, for example when you change leftover cash after your trip. It's lower than the mid-market rate.
The gap between the buy and sell rates is the price of the service. The wider the gap, the more expensive it is to exchange money. Airport exchange desks typically have wider gaps.
3. How your card's rate is set
When you pay by card abroad, the amount is converted into your currency at a rate set by the card network (such as Visa or Mastercard) and your bank. Many banks also add a foreign transaction fee. That's why the amount on your statement may differ slightly from the figure you worked out at the till. The rate can also change between the day you pay and the day the transaction is processed.
4. Watch out for dynamic currency conversion
A card machine or ATM may offer to charge you in your home currency. This is dynamic currency conversion (DCC). It looks convenient, but the conversion is done by the machine's provider instead of your bank, usually at a less favourable rate. Decline it and always choose the local currency. For more, see Card or cash abroad?
5. Add a buffer to your budget
When you plan your trip budget, don't treat every foreign-currency cost as fixed at today's rate. Rates can move between booking and paying, and fees and small charges add to the total. Adding a buffer of around 5–10% to your foreign-currency costs helps you avoid surprises at the end of the trip, especially if there's a long gap between booking and paying.
6. Check the currency code
The same symbol can mean different currencies: $ is used for the US, Canadian and Australian dollars and the Mexican peso, and kr can mean several Scandinavian currencies. When booking and comparing prices, look at the three-letter currency code (USD, CAD, EUR and so on) rather than the symbol. For every country's currency and code, see our world currencies table.
Example: the real cost of a one-week trip
Imagine spending a total of €600 by card during a week in a eurozone country. Assume a rate of 1 EUR = 1.15 USD and a 3% foreign transaction fee (example values):
- Converted amount: 600 × 1.15 = $690.00
- Fee: 690 × 3% = $20.70
- Real total: $710.70
If you also accepted the home-currency option at the card machine for some purchases, you'd have paid a worse conversion rate on top of the fee for those transactions. Percentages that look small become a noticeable amount over a whole week.
Common mistakes
- Not checking the currency code: Booking or paying in the wrong currency.
- Forgetting the fee: Treating the converted amount as the real cost.
- Accepting the card machine's or ATM's home-currency offer: Usually the most expensive option.
- Treating your budget as fixed at one rate: Rates change, so leave a buffer.
- Changing large amounts at the airport: The rate gap is usually wider.
Make conversions easy with BudTrip
With BudTrip's currency converter you see local prices in your own currency instantly and decide faster. You record expenses in the currency you paid; when the final amount appears on your card statement, update the record to track the real cost, including your bank's rate and fees.
Last updated: 6 October 2026
Related guides:
