* Species: Different species of mice have different litter sizes.
* Age: Young mice tend to have smaller litters than older mice.
* Nutrition: Well-nourished mice tend to have larger litters.
* Environmental factors: Stress, overcrowding, and limited resources can all reduce litter size.
Generally, house mice (Mus musculus) can have anywhere from 4 to 12 pups in a single litter.
However, it's important to remember that this is just a range, and individual mice can have significantly more or fewer offspring. Mice also have a very short gestation period of about 19-21 days, and they can reproduce multiple times per year. This means that a single pair of mice can produce a large number of offspring in a relatively short amount of time.