Holidaymakers will get no gain in Spain by opting to get their euros in hotels, according to a survey.
Hotels in Spain's Costa del Sol are among the worst offenders for offering poor currency
rates, the poll from foreign exchange company Travelex found.
British tourists could also be ripped off by hotels in the Canary Islands, Corfu, Florida and Turkey.
Some hotels offer as little as 0.82 euros to the pound when the going rate at present for tourists is around 1.20 euros.
Travelex said some of the poorest deals for Britons are at all-inclusive hotels where holidaymakers can get free drinks but are paying over the odds for foreign currency.
Elvin Eldic of Travelex said: "All-inclusive holidaymakers no doubt enjoy the carefree option and ability to budget ahead of travelling.
"However, not considering their travel money before leaving could prove costly and those withdrawing money to fund activities outside their all-inclusive deals are being badly stung by hotel exchange bureaux charging high commission or offering extremely poor exchange rates."