Depends. Mia is 3 lbs. at 10 weeks, so I am guessing she is at least going to be 7-8 lbs full grown. I got a small size pet flys bag, which accomodates pets up to 11 lbs. We may or may not need to get another one in a couple of years depending on how much she grows. Right now its kinda big for her
but it comes with a blanket, which I spread over the base, and I also toss a plush toy in there. Mia seems pretty comfy in it. This is the one I have:
http://www.petflys.com/pawprincess.html
You might also consider going to a more upperscale pet store where they would have the bags on site (they had celltei, pet flys and a couple others at the one I went to), and try them out. It is very difficult to order online.
Good luck and have fun!
