UK holidaymakers are reportedly being collectively charged £1 billion a year by banks for paying by credit or debit card when abroad.
Standard credit and debit cards impose fees of nearly 3% on all spending, plus extra costs for using cash machines.
Customers are being encouraged to apply for cards with zero charges to make their holiday money go further.
For those using a standard credit card, the average “non-sterling transaction fee” is 2.8%, added to the amount spent, with some banks charging 2.99%.
The average fee on standard debit cards is almost as much.
And there are multiple charges for using a debit card to withdraw cash – an average of 2.5% on the whole amount, plus an extra fee of £1.39 on average just for using a foreign cash machine.
The most recent figures from banks show that UK holidaymakers are spending more than £32 billion a year on their cards while overseas.
The charges on that spending are having a “huge impact on consumers’ pockets”, according to the foreign exchange specialists, FairFX, which analysed the charges for BBC News.
“When we’re on holiday it’s easy to turn a blind eye to what we think is just a few quid,” said FairFX chief executive Ian Strafford-Taylor.
But banks say using cards overseas is a safe, flexible and cost-effective way of paying.
UK Finance, the body which represents banks, said that some banks offer alternative credit cards which have no fees when people spend overseas.