How Long Do Mice Live?
Pet mice live 1.5 to 2.5 years, the shortest run of any common pet. They are still worth doing properly: female groups, clean air, a lean diet and quick vet care turn 18 months into 30.
Mouse age in human years
Life-stage equivalence scaled to the typical lifespan of the type you pick. Enter your mouse's age.
How long do pet mice live? The numbers
| Type | Typical | Excellent care | Notes |
|---|---|---|---|
| Fancy mouse, good care | 1.5 to 2.5 | 3 | Females in groups; males alone or neutered |
| Female | 1.5 to 2.5 | Mammary tumours common | |
| Male | 1.5 to 2.5 | Fight if housed together; smell more | |
| Wild mouse | under 1 | Not a pet |
Mouse years to human years
Scaled to a typical pet (fancy) mouse lifespan of about 2 years. Pick a different type in the converter above and the numbers shift with it.
| Mouse age | Human equivalent | Life stage |
|---|---|---|
| 3 months | ~16 | Youngster |
| 6 months | ~26 | Young adult |
| 1 year | ~43 | Middle-aged |
| 1.5 years | ~60 | Senior |
| 2 years | ~75 | Very senior |
| 2.5 years | ~86 | Very senior |
| 3 years | ~95 | Very senior |
| 4 years | ~110 | Very senior |
Life-stage equivalence, not biology: no validated ageing clock exists for pet mice. It is still the right way to think about vet schedules and senior care.
What actually adds months
Females in groups, males alone. Female mice are social and do best in threes or more; intact males fight to injury and are kept singly or neutered. A single female is a stressed female.
Dust-free bedding and ventilation. Mycoplasma-linked respiratory disease flares with ammonia and dust. Paper bedding, no pine or cedar, a well-ventilated cage cleaned often.
A lean diet. Lab blocks or a quality mix plus small amounts of vegetables. Fat mice get tumours and heart disease sooner.
Space to climb and dig. A big cage or tank with deep bedding, ropes, wheels (solid, 15 cm plus) and hides. Enrichment is welfare and lifespan.
Check for lumps weekly. Mammary tumours in females are extremely common; small ones can be removed. Any lump gets a vet look.
A vet who sees mice. Sneezing, hunched posture, laboured breathing or weight loss: early antibiotics and support add months to a short life.
Mouse lifespan FAQ
How long do mice live?
Pet mice typically 1.5 to 2.5 years, occasionally 3. Wild house mice rarely pass a year. Laboratory mice under ideal conditions have reached 4 or more.
How old is a 1-year-old mouse in human years?
By life stage, roughly a person in their early forties. An 18-month-old mouse is a senior, like someone around 60. Use the converter above.
Do male or female mice live longer?
Similar on average. Females face mammary tumours; males face fight injuries if housed together and are usually kept singly.
What do pet mice die of?
Tumours (especially mammary in females), respiratory disease, and old-age organ failure. Injuries from falls or fights and neglect of small illnesses account for the rest.
Can mice live 3 years?
Some do, with group housing, clean air, a lean diet and quick vet care. Plan for two.
Do mice need company?
Females do; keep them in groups of three or more. Males fight and are kept alone unless neutered.
Related tools
Sources: Merck Veterinary Manual on mouse disorders (mammary neoplasia, respiratory disease); RSPCA mouse care guidance; published laboratory mouse longevity data. Last reviewed August 2026.