The Consumer Council is advising travellers heading off on summer holidays to change their money before they reach the airport or ferry terminal.
Holly MacLennan from the council said people should make sure they're not spending more than needed on commission, charges or to withdraw money at an ATM abroad.
"It's likely you'll find a better deal changing your money before travelling rather than at the airport, ferry terminal or once abroad," she said.
"Try checking with banks, post offices, online, local shops or bureaux de change for the best exchange rate. Of course you can still convert money at the airport or ferry terminal, but remember you are a captive customer so may not get the best rate.
"Some people might not want to carry large sums of cash, which is understandable, but in that case consider how you'll pay for things abroad. If you're planning to use a debit or credit card to withdraw cash make sure to check what charges apply. It's also worth letting your bank know you're going away so they don't block your card."
To find out more about travel money, log on to www.consumer council.org.uk/publications or telephone 0800 121 6022.