ATM at CDG airport

"With conversion" means you are giving the owner of the ATM a blank check to use any exchange rate it wants to turn the euros you've requested into a US $ amount which will show up on your bank statement.

"Without conversion" means the transaction will be recorded in euros, and you will get a very reasonable exchange rate that's not far off the interbank rate you will find if you Google.

The right answer is always "without conversion" unless you just want to give money away.

Your bank, of course, may charge fees of its own.

I agree with acraven and it sounds like you are using one of the Travelex ATMs at CDG. There are two HSBC ATMs in terminal 2. Using the HSBC machines will not expose you to excessive fees.

Great! Good info. thanks so much, very educational.

The formal name for what you are asking about is "dynamic currency conversion" or DCC. There's nothing "dynamic" about it; it's just a rip-off.

Until recently, it was not present at European ATM's, but just in the past few years, it's become more and more prevalent, in more and more countries (Spain, Switzerland, etc). It's been present with credit card transactions for longer, but again, it's more prevalent now than before with these too.

It is sometimes phrased in sneaky ways. For instance, "would you like to lock in a rate of $XXX.xx?" Any time you see dollars in Europe, run; always choose local currency. Your bank will process the transaction at a much better rate than you get with DCC.

thanks to you all. great info. very helpful.