Not necessarily true about airport ATMs. Every airport is different and some have rip-off ATMs in prominent places as well as proper bank ATMs which are more hidden. It would be best to search for info about a specific airport shortly before you plan to travel through there.

For Visa cards you can find out the exchange rate you will be charged in advance (as in just before you put your card in an ATM - not weeks before) e.g. https://www.visa.co.uk/support/consu...alculator.html