One in four Brits have failed to check the currency exchange rates of a country before flying into it.
After all the prepartion that goes into the holiday it seems that they forget about the most imporant part - the money you need whilst over there.
The research also reveals that more than half of Brits have chosen a payment method on holiday based on convience this year, with only one in 10 choosing a payment method because they think it's the cheapest way to spend.
Russia comes out top as the country with the most confusion surrounding its currency; the average British traveller estimated that £100 is worth just over 1,000 RUB, when in fact you need to withdraw 4,500 RUB to get one hundred pounds' worth.
The research conducted by Capital One, found that we've also got it drastically wrong in our favourite holiday destinations. Based on an average weekly holiday spend of £1,091, we've misjudged by £118 per week in Europr, £95 a week in America and over £500 in South Africa - because of our lack of currency knowledge.
"Would you pay for your weekly shop and not check the bill? The same applies here," says Brian Cole, managing director of Capital One.
"It's never advisable to withdraw hundreds of pounds for a holiday without checking that you are getting the best exchange rate. In an age where information on foreign currency is readily available, it is surprising to see the amount of money that we are still wasting on holiday just because we haven't taken the time to check the exchange rate ot the best payment method."