How it's calculated
human years = 15 (year 1) + 9 (year 2) + 4 × (cat age − 2)
cat age in years. First year of life = 15 human years, second year = +9, each year after = +4. Outdoor or mixed lifestyle adds 1–2 years to the result.
Reference ranges
| Cat age | Human years |
|---|---|
| 1 year | 15 |
| 2 years | 24 |
| 5 years | 36 |
| 10 years | 56 |
Common questions
Why does the first year count for so much?
Cats mature very quickly early on, reaching the rough equivalent of a 15-year-old human by their first birthday.
When is a cat considered a senior?
Most vets consider cats senior from around 11 cat years, which is roughly the early sixties in human terms.