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Cat Age Calculator
Cats grow up fast and then age gently. Enter your cat’s age to convert it to human years with the guideline vets use — 15 years for the first year, 9 for the second and 4 for every year after — and see which life stage your cat is in.
- Life stage
- Young adult
- By the old “× 7” rule
- 21 years
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Formula
How to use it
- Enter your cat’s age in years.
- Add months for a kitten or for extra precision.
- Read the equivalent human age and the life stage.
Worked examples
A 3-year-old cat
- Age in human years
- 28 years
- Life stage
- Young adult
- By the old “× 7” rule
- 21 years
A 12-year-old cat
- Age in human years
- 64 years
- Life stage
- Senior
A 6-month-old kitten
- Age in human years
- 10 years
- Life stage
- Kitten
An 8-year-old cat
- Age in human years
- 48 years
- Life stage
- Mature adult
Where the numbers come from
The 15 – 9 – 4 pattern is the comparison chart published with feline life-stage guidance from veterinary bodies including the American Animal Hospital Association, the American Association of Feline Practitioners and International Cat Care. For kittens, this calculator follows the same chart’s milestones: about 10 human years at six months, 15 at one year and 21 at eighteen months.
Unlike dogs, cats vary little in size between breeds, so no size adjustment is needed.
Life stages
The 2021 AAHA/AAFP Feline Life Stage Guidelines use four stages: kitten (birth up to 1 year), young adult (1 to 6 years), mature adult (7 to 10 years) and senior (over 10 years). Vets generally recommend more frequent check-ups from the senior stage on.
A converted age is a guide to life stage, not a health assessment. Indoor cats commonly live into their mid to late teens, and some pass 20 — the equivalent of 96 human years.
Questions people ask
How old is a 1-year-old cat in human years?
About 15. A two-year-old cat is about 24.
How old is a 10-year-old cat in human years?
About 56: 24 for the first two years plus 4 for each of the next eight.
How old is a 15-year-old cat in human years?
About 76.
At what age is a cat a senior?
Over 10 years, under the 2021 AAHA/AAFP life-stage guidelines. That corresponds to about 60 human years.