House mice have a polygynous mating system, where each male mates with multiple females. Males sing when they smell females who are ready to mate, which might attract females.

Mating System: polygynous

House mice are able to reproduce throughout the year, often having 5-10 litters each year when conditions are favorable. Pregnancy lasts for 19 to 21 days and 5 to 6 young are born per litter, though there can be as many as 12. Young weigh about 1 gram at birth and are naked, blind, and helpless. At 10 days old they have fur and at 14 days old they open their eyes. The young are nursed for 21 days and reach adulthood at 5 to 7 weeks old.

Breeding season: Throughout the year

Range number of offspring: 3.0 to 12.0.

Average number of offspring: 5.0.

Range gestation period: 21.0 (high) days.

Average weaning age: 21.0 days.

Range age at sexual or reproductive maturity (female): 5.0 to 7.0 weeks.

Range age at sexual or reproductive maturity (male): 5.0 to 7.0 weeks.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous

Average birth mass: 1.25 g.

Average number of offspring: 7.

Young mice are cared for in their mother's nest until they reach 21 days old. Soon after this most young mice leave their mother's territory, though young females are more likely to stay nearby.

Parental Investment: altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)