If you carry out a transaction using your card in a currency other than sterling, it will be converted to sterling on the day the transaction is processed by our card scheme providers at a wholesale rate of exchange (in addition cash withdrawals will incur a fee of 2.5% - minimum £5).
For an indication of that exchange rate, you can see the Visa wholesale rate of exchange at Visa Europe FX Calculator. This is an "indication" because transactions are processed when the retailer passes them on to the scheme provider, which is generally not on the same day the transaction took place.
To compare the rates and charges for using your card abroad, please see our using your cards abroad page.