Brits who travelled on cheap flights abroad spent a collective total of £3.87 billion in foreign currencies during the past 12 months.
This is according to research from Sainsbury's Travel Money, which found that 11.3 million UK holidaymakers had spent the collective total over the last year.
It was also revealed that the average amount withdrawn from an overseas cash machine is the equivalent of £150, although many Brits were subjected to a surcharge when withdrawing their holiday money.
Scott Gorman, head of Sainsbury's Travel Money, warned travellers about the potential pitfalls of pre-loaded currency travel cards, which he said give many a "raw deal".
"These cards are supposed to give travellers financial peace of mind whilst they are away from the UK and in theory should mean that they don't find themselves overspending and accruing charges for overseas transactions," he explained.
"On the contrary, our research shows that almost three in four of these specialist prepaid cards are charging people every time they wish to access their spending money from an overseas cash machine."
Findings from Santander Credit Cards published last month revealed that Brits have amassed £1.75 billion of leftover holiday cash, with £42 million of this being donated to charity.