When I had pet mice (I'm in the UK) they were between about 22g (blue broken satin longhair doe, if anyone is interested) and 35g (black satin banded doe). I only weighed the first couple of mice I had though so I may well have had some bigger. The mouse in the photo was 15g and she was mine (bought from a pet shop injured, rehabilitated and then rehomed to a friend who had 2 does from my first ever litter). The cream doe in the photo was weighed for comparison and was 100g. I think this is exceptional though, I'm sure that my current creams don't weigh that much!