Holidaymakers spend an average of £50 at the airport on items such as books, sun cream and medication.
A quarter of people spend up to £100, resulting in the UK spending £2.8 billion on pre-holiday items.
42% of parents spend more than £100 on necessities such as keeping children amused on the journey.
Items such as taxis, excursions, ice creams and drinks cost people an average of £218 when they are away, meaning that Britons abroad spend £15 billion on holiday outlay, the research by Asda Money found.
The most expensive cost is meals out, with holidaymakers spending more than £100 on these.
Head of Asda Money Kirsty Ward said: “Holidaymakers are planning on spending a fortune on a much needed break this summer, but on top of flights, accommodation, outings and more, they are spending billions of pounds in preparing and enjoying themselves once they hit the sunshine.
“Mums and Dads need to make sure they are budgeting way ahead of their trip and to not over spend before and during as they could come back to a financial mess.”
She added: “Our research has found that despite knowing they won’t get the most competitive rates, a fifth of people continue to purchase their holiday money at the airport, last minute or at the ATM once they’re away.”