That's really a 'how long is a piece of string?' question - it does ddepend on what you intend to do while you are there. Base your spending on the fact that Paris is a capital city, so taxis and restaurants are expensive. If you are eating out, allow yourself about �20 per head for a decent meal with wine, and adjust your budget accordingly, but if you explore away from the main tourest routes, you can find cheaper places to eat, and to stay if you have no accomodation sorted. Have a word with a few travel agents who deal with Paris and get some advice on where to go, and how much it's going to cost, and work out your spending from there, based on what you want to afford.