Spending abroad costs more than the exchange rate suggests, and the difference is rarely a single line on a statement. The charges are layered and some of them are optional.
The interbank rate is not what customers get
Currencies trade between institutions at a wholesale rate that moves continuously. Retail customers receive a rate derived from it with a margin applied.
That margin is the primary cost and it is invisible, because it appears as the rate itself rather than as a charge. A poor rate and a low advertised fee often coexist.
Card networks apply their own rate at settlement, and the issuing bank may add a further percentage on top. Two cards on the same network can therefore differ.
Dynamic conversion is the expensive option
When a terminal abroad offers to charge in the home currency, that is a conversion performed by the merchant's payment provider. The rate is set by that provider.
The margin applied is typically well above what a card network would use. The offer is presented as a convenience and is consistently the worse choice.
Declining it and paying in the local currency hands conversion to the card network. This single decision is usually the largest saving available.
ATM charges stack in several places
A withdrawal abroad can carry an operator fee at the machine, a foreign transaction fee from the issuer, and a conversion margin. Each is charged by a different party.
Machines in airports, hotels and tourist districts frequently carry the highest operator fees. Bank-operated machines away from those areas generally charge less.
Because a flat fee is spread across the amount withdrawn, fewer larger withdrawals cost less than many small ones. That trades against carrying more cash.
Bureau spreads work differently
Exchange bureaux earn on the gap between their buy and sell rates rather than on a stated fee. A wide spread with no commission can cost more than a narrow spread with one.
The spread widens with location and convenience. Airport and border bureaux price against travellers with no alternative, which is the same captive logic seen elsewhere.
Comparing the buy and sell figures on the board reveals the cost immediately. A bureau showing rates far apart is expensive regardless of what the sign claims.
Working out the true cost
The only reliable comparison is the total home currency amount for a fixed purchase. Rates, fees and commissions are not comparable individually.
Checking the wholesale rate before travelling gives a benchmark to measure against. Anything within a small margin of it is reasonable.
Products differ substantially, and terms change, so the answer is specific to the card and country rather than general. Testing one small transaction early reveals what a trip will actually cost.