An opossum ages about 22 human years every year.
A one-year-old opossum is roughly 38 in human terms. Most never reach four.
The Virginia opossum is the textbook example of rapid ageing in mammals. It is one of the most studied animals in the biology of senescence, because almost everything about it happens quickly.
Opossum years to human years
| Opossum's age | In human years | Life stage |
|---|---|---|
| 3 months | 4 | Juvenile |
| 6 months | 16 | Juvenile |
| 9 months | 29 | Adolescent |
| 1 years | 38 | Adolescent |
| 1.5 years | 51 | Adult |
| 2 years | 60 | Adult |
| 2.5 years | 67 | Mature |
| 3 years | 73 | Senior |
| 3.5 years | 78 | Geriatric |
| 4 years | 82 | Geriatric |
Based on a median lifespan of about 3.5 years in captivity. In the wild the figure is closer to 1.5 to 2 years; the documented maximum is 6.6.
Why they age so fast
In the early 1990s the biologist Steven Austad studied opossum populations on Sapelo Island, off the coast of Georgia, which had been isolated from mainland predators for thousands of years. Mainland opossums showed severe physical decline by their second year. The island population, under far less predation pressure, aged measurably more slowly and lived longer.
It became one of the clearest field demonstrations of an important idea in ageing research: that lifespan is shaped by predation pressure. Where an animal is unlikely to survive long anyway, there is little evolutionary pressure to maintain the body past early adulthood.
The practical consequence for an opossum is stark. Cataracts commonly appear in the second year. Arthritis and muscle loss follow quickly. An opossum that reaches three has lived a long life.
Can you keep an opossum as a pet?
In most US states, no — not without a wildlife rehabilitation permit. Rules vary considerably and some states prohibit it outright. Check your state and local regulations before acquiring one, and be aware that a wild-caught adult rarely does well in captivity.
Licensed rehabilitators do care for opossums, usually orphaned juveniles, and non-releasable animals sometimes live out their lives in permitted care. That is the context in which most people legitimately encounter an opossum's full lifespan.
Worth knowing if you care for one
An opossum passes a human-equivalent birthday roughly every two to three weeks. Across a whole life that is about forty moments worth noticing, compressed into the span most people take to choose a sofa. If you are caring for one, the calendar moves faster than your instincts expect.
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Open the calculatorCommon questions
How long do opossums live?
About 1.5 to 2 years in the wild and roughly 3.5 in captivity. The documented maximum is 6.6 years. They are among the shortest-lived mammals of their size.
How old is a 1 year old opossum in human years?
About 38. Opossums reach sexual maturity at around six months and are physically declining well before their second birthday.
Why do opossums age so quickly?
High predation pressure in the wild means few individuals survive long, which reduces the evolutionary advantage of maintaining the body past early adulthood. Steven Austad's work on Sapelo Island demonstrated this by showing that an isolated, predator-free population aged more slowly.
Is it legal to keep an opossum?
In most US states it requires a wildlife rehabilitation permit, and some states prohibit it entirely. Check your state and local rules first.
Do opossums carry rabies?
Very rarely. Their body temperature is low enough that the rabies virus survives poorly in them, which is why opossum rabies cases are unusual compared with other wild mammals.