The next time you change your U.S. dollars into foreign currency at an airport overseas, you might want to think about the markup on the exchange rate. 

 

Consider this: in London alone, both Heathrow and Gatwick Airport earn close to 75 million pounds a year from just the rent they charge to money changers in their terminals.

 

And how do the money changers afford that rent? They can afford it by jacking up their margins on exchange rates. In some cases, it’s up to 15% more than local banks outside the airport.

 

In London at least, one in every 10 passengers does money changing at the airport.

 

Here’s what you should do: whether you’re traveling to London or anywhere else, use a debit card that doesn’t charge you a fee to use foreign ATMs. And then, take out only what you need on a daily basis. The reason? At the end of the trip, if you budget wisely, you won’t have to do any money exchange back at the airport.