Cats grow up quickly, then age at a steady pace of about four human years for every cat year.
| Cat age | Human years | Life stage |
|---|---|---|
| 1 year | 15 | Young adult |
| 2 years | 24 | Young adult |
| 3 years | 28 | Young adult |
| 4 years | 32 | Young adult |
| 5 years | 36 | Young adult |
| 6 years | 40 | Young adult |
| 7 years | 44 | Mature adult |
| 8 years | 48 | Mature adult |
| 9 years | 52 | Mature adult |
| 10 years | 56 | Mature adult |
| 11 years | 60 | Senior |
| 12 years | 64 | Senior |
| 13 years | 68 | Senior |
| 14 years | 72 | Senior |
| 15 years | 76 | Senior |
| 16 years | 80 | Senior |
| 17 years | 84 | Senior |
| 18 years | 88 | Senior |
| 19 years | 92 | Senior |
| 20 years | 96 | Senior |
| 21 years | 100 | Senior |
| 22 years | 104 | Senior |
| 23 years | 108 | Senior |
| 24 years | 112 | Senior |
| 25 years | 116 | Senior |
A cat is about 15 in human years by their first birthday and 24 by their second. After that, each year adds about four human years, so a 10-year-old cat is about 56 and a 15-year-old about 76.
The life stages come from the AAHA and AAFP feline life stage guidelines, used by vets:
How long do cats live? A 2024 Royal Veterinary College VetCompass study of UK cats found an average life expectancy of 11.74 years, which is like a person in their early sixties. Many cats live well beyond that, and indoor cats and those kept at a healthy weight often do best.
About 15. A one-year-old cat has finished most of its growing and is roughly as mature as a teenager.
About 36. That's roughly like someone in their thirties, and a cat this age is classed as young adult.
About 56. That's roughly like someone in their fifties, and a cat this age is classed as mature adult.
About 64. That's roughly like someone in their sixties, and a cat this age is classed as senior. It's past the average UK life expectancy, but plenty of cats live much longer.
About 76. That's roughly like someone in their seventies, and a cat this age is classed as senior.
About 96. That's roughly like someone over 90, and a cat this age is classed as senior. Reaching 20 is a real achievement for a cat.
Life stages: AAHA/AAFP Feline Life Stage Guidelines. Life expectancy: Royal Veterinary College VetCompass (2024).