Cats age fast in their first two years, then settle into a steadier pace. This calculator converts your cat’s age into human years and tells you which life stage it is in — from kitten to geriatric. It also adjusts for lifestyle: outdoor and indoor-outdoor cats live harder lives, so their human-equivalent age is nudged slightly higher.
How it works
The conversion uses the widely accepted veterinary scale, applied in three bands:
- Year 1: the cat ages the equivalent of 15 human years.
- Year 2: adds another 9 years, reaching 24 by age 2.
- Each year after: adds roughly 4 human years.
The formula for a cat older than 2 is therefore human = 24 + (cat years − 2) × 4. For an outdoor cat, the result is multiplied by 1.08. The tool then assigns a life stage by age: kitten (under 0.5), junior (under 2), adult (under 7), mature (under 11), senior (under 15) and geriatric (15+).
Example
A 3-year-old indoor cat:
24 + (3 − 2) × 4 = 28 human years — life stage: Adult.
| Cat age | Human years (indoor) |
|---|---|
| 1 | 15 |
| 2 | 24 |
| 3 | 28 |
| 7 | 44 |
| 15 | 76 |
The same 3-year-old as an outdoor cat works out to about 30 human years (28 × 1.08). Everything runs in your browser with nothing uploaded.