Cat Age Calculator
Convert your cat's age to human years with the AAHA/AAFP feline life-stage chart (15 for the first year, 24 by two, then 4 a year) and see its life stage.
Cat Age Calculator: with the default inputs, human-equivalent age is 36.
Use decimals for kittens: 6 months = 0.5.
- Life stage
- Young adult (1–6)
- Old 'multiply by 7' rule
- 35
- Next life stage
- Mature adult at 7 (in 2 years)
Assumptions
- The 15/24/+4 chart is a convention for communicating life stage, not a biological measurement.
- Breed and size are not adjusted for, since they matter little in cats.
| Cat age | Human years | Life stage |
|---|---|---|
| 3 months | 4 | Kitten |
| 6 months | 8 | Kitten |
| 1 years | 15 | Young adult (1–6) |
| 2 years | 24 | Young adult (1–6) |
| 3 years | 28 | Young adult (1–6) |
| 4 years | 32 | Young adult (1–6) |
| 5 years | 36 | Young adult (1–6) |
| 6 years | 40 | Young adult (1–6) |
| 7 years | 44 | Mature adult (7–10) |
| 8 years | 48 | Mature adult (7–10) |
| 9 years | 52 | Mature adult (7–10) |
| 10 years | 56 | Mature adult (7–10) |
| 11 years | 60 | Senior (11–14) |
| 12 years | 64 | Senior (11–14) |
| 13 years | 68 | Senior (11–14) |
| 14 years | 72 | Senior (11–14) |
| 15 years | 76 | Geriatric (15+) |
| 16 years | 80 | Geriatric (15+) |
| 17 years | 84 | Geriatric (15+) |
| 18 years | 88 | Geriatric (15+) |
| 19 years | 92 | Geriatric (15+) |
| 20 years | 96 | Geriatric (15+) |
How this is worked out
The formula
year 1 = 15 human years year 2 = +9 (24 human years at age 2) each year after = +4 human age = 24 + 4 × (cat age − 2) for cats 2 and older
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Cat's age
- Use decimals for kittens: 6 months = 0.5.from 0.1 to 40 · defaults to 5
What you get back
- Human-equivalent agemain answer
- Life stage
- Old 'multiply by 7' rule
- Next life stage
What this assumes
- The 15/24/+4 chart is a convention for communicating life stage, not a biological measurement.
- Breed and size are not adjusted for, since they matter little in cats.
About this calculator
Cats grow up fast and then age slowly and steadily. Veterinarians' standard conversion, from the American Animal Hospital Association and the American Association of Feline Practitioners' feline life-stage guidelines, counts the first year as about 15 human years, the second as 9 more (24 at two), and each year after that as 4. A 5-year-old cat is roughly 36, a 10-year-old 56, and a 20-year-old 96.
Why not ×7?
The seven-times rule treats a 1-year-old cat as a 7-year-old child, but a yearling cat is sexually mature and fully grown — closer to a teenager. It also makes a 15-year-old cat "105" when 15 is a common age for an indoor cat to reach in reasonable health. The 15/24/+4 chart matches feline biology far better.
Life stages
The 2021 AAHA/AAFP guidelines define four stages after kittenhood:
- Kitten — birth to 1 year. Rapid growth, vaccinations, neutering.
- Young adult — 1 to 6 years. Peak condition; the time to establish weight control and dental habits.
- Mature adult — 7 to 10 years. Roughly the human 40s and 50s. Weight gain and early kidney, thyroid and dental disease start to appear; annual bloodwork is recommended.
- Senior — 11 to 14 years. Human 60s and 70s. Twice-yearly checkups; watch for increased thirst, weight loss and changes in litter-box habits.
- Geriatric — 15 and over. Human 76+. Many cats do well into their late teens with monitoring.
Lifespans
Indoor cats commonly live 13–17 years and often past 20; outdoor cats average far less because of traffic, fights and disease. Unlike dogs, size has little effect on feline aging — a Maine Coon and a Siamese age at about the same rate — so no size selection is needed. Purebreds vary somewhat: Siamese and Burmese are long-lived, while some flat-faced breeds have more health issues.
Guessing a cat's age
For a rescue with unknown history, vets estimate age from teeth (adult teeth are in by 6 months; tartar and wear build with years), eye clarity (lens cloudiness appears from about 10), coat and muscle tone. Enter the estimate here for a human-year equivalent.
Frequently asked questions
▸How old is a 10-year-old cat in human years?
About 56. The first two years count as 24, and each of the next eight adds 4.
▸How old is a 1-year-old cat in human years?
About 15 — a fully grown adolescent. By age 2 a cat is roughly 24 in human terms.
▸When is a cat considered a senior?
From 11 years under the 2021 AAHA/AAFP guidelines (mature adult is 7–10). Many vets start senior wellness screening at 7.
▸Is one cat year seven human years?
No. Cats mature in their first year and then age about four human years per year. The ×7 rule understates a young cat's maturity and overstates an old cat's age.
▸How long do cats live?
Indoor cats typically 13–17 years, frequently over 20. The verified record is 38 years (Creme Puff, 1967–2005).
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