Guinea Pig Age Calculator
Turn your guinea pig’s birth date or age into human years, find their life stage, and see how far along their life journey they are.
Calculate your guinea pig’s age
Choose how you want to enter the age. Results update as you type.
Not sure? Use your best guess, or the date you got them minus their age at the time.
How old is my guinea pig in human years?
Guinea pigs grow up fast. They are adults by about six months old and typically live five to seven years, so each year of a guinea pig’s life covers far more development than a human year. There is no exact scientific formula, and different websites give very different numbers, from about 10 to 30 human years for a one-year-old guinea pig. Our calculator uses a clear, consistent method so you can see how the estimate is made.
| Guinea pig age | Human years (typical) | Likely range |
|---|---|---|
| 1 month | 3 | 3 |
| 3 months | 9 | 9 |
| 6 months | 18 | 18 |
| 1 year | 24 | 23 to 25 |
| 2 years | 35 | 32 to 39 |
| 3 years | 46 | 42 to 52 |
| 4 years | 57 | 51 to 66 |
| 5 years | 69 | 61 to 80 |
| 6 years | 80 | 70 to 94 |
| 7 years | 91 | 80 to 108 |
How the calculator works
We use two steps. First, a guinea pig reaches adulthood at about six months, which we match to 18 human years. Second, from six months onward we spread the rest of the life evenly, so that a typical lifespan of six years matches an 80-year human lifespan. Because guinea pigs live anywhere from about five to seven years, we also show a range, which is why older guinea pigs have wider ranges. Treat the result as a fun and useful guide, not an exact measurement.
Guinea pig life stages
| Life stage | Age | What to know |
|---|---|---|
| Baby | Under 1 month | Very fragile and still nursing or weaning. |
| Adolescent | 1 to 6 months | Still growing, with higher nutrition needs. |
| Adult | 6 months to 4 years | Fully grown and in their prime. |
| Mature | 4 to 5 years | Starting to slow down. Watch weight and teeth. |
| Senior | 5 years and older | Needs extra comfort and more regular vet checks. |
Life stages are a guide. Guinea pigs age at different rates, so ask an exotic animal vet if you are worried about your guinea pig’s health or age.
Frequently asked questions
How old is a 1-year-old guinea pig in human years?
A one-year-old guinea pig is roughly 24 in human years, a young adult. Estimates vary between websites because there is no exact formula.
How long do guinea pigs live?
Most guinea pigs live about 5 to 7 years with good care, and some live longer.
At what age is a guinea pig a senior?
Guinea pigs are generally considered seniors from about 5 years old, though some show signs of aging a little earlier or later.
How can I tell how old my guinea pig is?
It is hard to be exact. Young guinea pigs are smaller and lighter, and older guinea pigs may lose muscle tone and have thicker nails. An exotic animal vet can give the best estimate.