How Exchange Rates Actually Work
Every time you convert dollars into another currency, two numbers matter: the mid-market rate and the rate you're actually offered. The gap between them is where the real cost hides. Currency exchangers — whether banks, kiosks, or apps — buy currency wholesale at the mid-market rate and sell it to you at a marked-up price. That markup is their profit.
To know whether you're getting a fair deal, look up the current mid-market rate on a neutral source before you travel. Then compare whatever rate a provider quotes against that benchmark. A small spread (under 2%) is reasonable. A spread of 10% or more — common at airport kiosks — means you're leaving significant money on the table.
Mid-market rate
The midpoint between the buy and sell prices of two currencies on the global market. It's the 'true' exchange rate you see on Google or financial sites, and the benchmark against which all conversion offers should be compared.
Spread
The difference between the mid-market rate and the rate a currency exchanger actually offers you. The wider the spread, the more you're paying in hidden fees.
Dynamic currency conversion (DCC)
A service offered at some foreign card terminals that converts your purchase into US dollars on the spot. It typically uses an unfavorable rate — declining it and paying in the local currency is almost always the better choice.
Foreign transaction fee
A surcharge, usually 1–3% of each purchase, added by some card issuers when you use your card outside the US or in a foreign currency.
ATM network fee
A charge applied when you withdraw cash from an ATM outside your bank's network, often combined with a flat fee from the foreign bank's ATM itself.
Currency peg
When a country ties its currency's value to another currency (often the US dollar), keeping the exchange rate artificially stable rather than letting it float with the market.
Exchange rates also float constantly with global markets, so the rate today may differ from the rate next week. For a deeper look at all the costs that sneak into a trip, see our guide to hidden travel costs.
Where to Exchange Money — and Where to Avoid
Where you convert currency matters as much as when. Here's a practical breakdown:
| Airport kiosk exchange rate markup | Typically 10–15% above mid-market rate (General industry range; varies by provider and location) |
| Typical foreign transaction fee | 1–3% per purchase (Standard range across major US card issuers) |
| Currencies accepted nearly worldwide | USD, EUR, GBP (most widely recognized) (General traveler guidance; verify locally) |
| Best benchmark for exchange rates | Mid-market rate (Google Finance, XE.com) |
| Dynamic currency conversion cost | Often 3–7% above mid-market rate (General consumer finance guidance) |
| Recommended cash reserve for travel | Small amount for emergencies and cash-only vendors (Standard travel planning advice) |
- ATMs abroad: Generally offer rates close to the mid-market rate, making them one of the more cost-efficient options. The catch is ATM fees — both your home bank's out-of-network fee and the foreign ATM operator's surcharge. Look for a checking account that reimburses ATM fees internationally.
- Your home bank before departure: Many US banks will order foreign currency at competitive rates, often with a few days' lead time. Rates vary, so compare against the mid-market benchmark.
- Airport kiosks: Convenient but consistently among the most expensive options. Use them only if absolutely necessary, and only for a small amount.
- Hotel desks: Similar to airport kiosks — convenient, but the markup is often steep.
- Foreign bank branches: Sometimes offer better rates than exchange kiosks in the same city. Worth checking at your destination.
Building a realistic currency budget is part of planning your full trip budget well before departure.
Cards Abroad: What to Watch For
Paying by card internationally is often convenient and secure — but two charges can quietly inflate every transaction.
10–15%
Extra cost at airport currency kiosks
Airport exchange counters routinely apply markups well above the mid-market rate, making them one of the costliest places to convert money.
3–7%
Hidden cost of dynamic currency conversion
When a foreign terminal offers to charge you in US dollars, the convenience typically costs 3–7% above the mid-market rate.
$0
Foreign transaction fee on many travel cards
Several card issuers offer cards with no foreign transaction fees — checking this before you leave is one of the easiest ways to avoid unnecessary charges.
Foreign transaction fees are added by some card issuers on purchases made outside the US or charged in a foreign currency. Check your card's terms before you travel; many travel-oriented cards waive this fee entirely. If yours doesn't, it's worth considering whether to open one before a major international trip.
Dynamic currency conversion (DCC) is a trickier trap. When a merchant or ATM abroad offers to process your payment in US dollars instead of local currency, it sounds helpful — but the exchange rate applied is typically far worse than what your card issuer would use. Always choose to pay in the local currency and let your card handle the conversion.
For a broader look at how cash and cards compare in everyday spending decisions, read our cash vs. card breakdown.
Always Verify Entry and Financial Rules Officially
Some countries limit how much cash you can bring in or out, and rules change. Before traveling, check the US Department of State country information page and your destination country's customs authority for current requirements. This article provides general educational guidance only, not legal or financial advice.
Cash vs. Cards: Striking the Right Balance
Neither cash nor cards alone is the perfect solution abroad. Cards offer fraud protection and often strong exchange rates, but some destinations — markets, rural areas, small restaurants — operate on cash only. A power outage or technical issue can also leave card-only travelers stranded.
A practical approach: carry a modest amount of local cash for small purchases and emergencies, and use a no-foreign-transaction-fee card for larger expenses. Withdraw cash in larger, less frequent amounts from ATMs to minimize per-withdrawal fees rather than making many small withdrawals.
For anyone building out their full international travel checklist — covering visas, vaccinations, and more — our step-by-step international travel planning guide covers the whole picture.
The content on this site is for informational purposes only and is not a substitute for professional advice. Always consult a qualified professional for guidance specific to your situation.