How often do mice have babies?

According to a University of Michigan resource on breeding mice for laboratory purposes, a female mouse can give birth to between four and eight litters each year. Each litter consists of an average of between six to eight mice.

A female mouse reaches sexual maturity at between 6 and 8 weeks old. The gestation period for a litter typically lasts between 19 and 21 days. Mice are very common in laboratory research, especially in genetics, in part because of this quick generation time, but this quality also makes them a pervasive pest animal. Besides their quick generation cycle, mice are also beneficial to genetic research because most of their genes have human homologs.