Updated
Cat age calculator
Cat years to human years by the convention every reputable source uses — about 15 human years for the first cat year, 9 for the second, then 4 a year — with the life stage named the way the feline guidelines name it. It is a convention, not a measurement, and this page says so.
28 human years
Life stage: young adult.
- Convention: 15 for year one, +9 for year two, then +4 a year
- 28 human years
- Life stage (AAFP/ISFM 2021)
- young adult — kitten to 1, young adult 1–6, mature adult 7–10, senior 11+
- Senior from
- 11 years: the guidelines recommend check-ups twice a year from then on
What this means
The convention front-loads the early years because a one-year-old cat is fully grown and can breed, which no 7-year-old child can. After the second year the curve is a straight line: every cat year is worth about four human years, whatever the breed.
Indoor cats live longer than outdoor cats on average — often by several years — but that changes life expectancy, not the conversion. This page does not add a fake indoor or outdoor adjustment, because no source quantifies one.
Two of the top-ranking calculators misquote the convention and two apply unsourced slow-downs after 14; this page keeps 15, 9 and 4 throughout and names where they come from.
Cat age chart: cat years to human years
Cat years to human years for every age from 1 to 20, with the life stage the feline guidelines give each age.
| Cat years | Human years | Life stage |
|---|---|---|
| 1 | 15 | young adult |
| 2 | 24 | young adult |
| 3 | 28 | young adult |
| 4 | 32 | young adult |
| 5 | 36 | young adult |
| 6 | 40 | young adult |
| 7 | 44 | mature adult |
| 8 | 48 | mature adult |
| 9 | 52 | mature adult |
| 10 | 56 | mature adult |
| 11 | 60 | senior |
| 12 | 64 | senior |
| 13 | 68 | senior |
| 14 | 72 | senior |
| 15 | 76 | geriatric |
| 16 | 80 | geriatric |
| 17 | 84 | geriatric |
| 18 | 88 | geriatric |
| 19 | 92 | geriatric |
| 20 | 96 | geriatric |
When to see a vet
- Your cat is 11 or older: the feline guidelines recommend twice-yearly check-ups, with weight, blood pressure and kidney checks, because the diseases of age are far easier to manage when caught early.
- A cat of any age that is drinking more, losing weight, hiding, or has stopped grooming.
Formula and sources
Sources reviewed 18 September 2026. Each names the figure it supports.
- Human-year equivalent (15, +9, then +4 a year — a convention, not a measurement) — International Cat Care, "How to tell your cat’s age in human years"
- Life stages (kitten, young adult 1–6, mature adult 7–10, senior 11+) and senior check-ups — AAFP/ISFM Feline Life Stage Guidelines, 2021 (Journal of Feline Medicine and Surgery 23(3))
This page is an educational estimate, not veterinary advice.
Frequently asked questions
How old is my cat in human years?
About 15 human years for the first year, 24 by the end of the second, then add 4 for every year after that. A 3-year-old cat is about 28; a 10-year-old is about 56; a 15-year-old is about 76.
Is one cat year seven human years?
No. The "times seven" figure treats every year the same, and cats mature in their first year. The convention used by veterinary bodies counts the first two years as about 24 human years and each year after as about four.
What are the feline life stages?
The 2021 AAFP/ISFM guidelines name four: kitten (up to 1 year), young adult (1–6), mature adult (7–10) and senior (11 and over). "Geriatric" for 15+ is this site’s own label for the copy; the guidelines fold it into senior.
Can I enter my kitten’s age in months?
Yes: enter 0 years and the months. Under one year the convention is stretched in proportion to the first-year figure of 15 and the result is labelled a linear estimate, because the convention itself only speaks in whole years.