Be aware that PayPal calculates 2.5% on top of a bad (in your favour) currency exchange rate.
Example: You want to pay an British Merchant 420 GBP. By default you PayPal does the currency conversion for you. This boils down to a bad exchange rate of:
At the same time a simple google conversion yields:
~18,76 EUR difference!
To remedy this just go to:
And choose to NOT use the PayPal conversion method. (Only for Credit Cards)
Leave a comment if it works for you.