Blog · 7 November 2026
How old is my cat in human years?
The short answer: a 1-year-old cat is about 15 in human years, a 2-year-old is about 24 — and after that, each cat year adds roughly 4. A 10-year-old cat is about 56; a 15-year-old is about 76. The rule behind those numbers is the “15-9-4” chart vets use, from the AAHA/AAFP Feline Life Stage Guidelines, and this page explains it, gives you the full chart, and shows how age maps to the life stages your vet plans care around.
The 15-9-4 rule
The conversion the American Animal Hospital Association (AAHA), the American Association of Feline Practitioners (AAFP) and International Cat Care agreed on works in three steps. The first year of a cat's life equals about 15 human years, because a kitten goes from newborn to sexually mature in under 12 months. The second year adds about 9 more, taking a 2-year-old cat to 24. Every year after that adds about 4. For a cat over 2, the formula is simple: human years = 24 + 4 × (cat age − 2).
It is a convention built on developmental milestones, not a biological law — a lean, active 12-year-old can be in better shape than an overweight 8-year-old, and individual cats vary with breed, weight and health. But as a planning tool it is the standard vets use, and it is the same scale our cat age calculator uses.
Cat years to human years chart
| Cat's age | Human years | Life stage |
|---|---|---|
| 1 year | 15 | Junior |
| 2 years | 24 | Junior |
| 3 years | 28 | Prime |
| 5 years | 36 | Prime |
| 7 years | 44 | Mature |
| 10 years | 56 | Mature |
| 12 years | 64 | Senior |
| 15 years | 76 | Geriatric |
| 20 years | 96 | Geriatric |
Source: 2021 AAHA/AAFP Feline Life Stage Guidelines. Worked example: a 10-year-old cat = 24 + (8 × 4) = 56 human years. For a dog the curve is different — dogs follow the AKC size chart, explained in how old is my dog in human years.
Life stages: what the age actually changes
The 2021 AAHA/AAFP guidelines group cats into four age-related stages (plus an end-of-life stage that can occur at any age): kitten (birth to 1 year), junior (1–2 years), prime (3–6 years), mature (7–10 years), senior (11–14 years) and geriatric (15 years and over). Each stage carries different care — kitten vaccinations and spay/neuter timing, prime-age weight and dental checks, senior bloodwork and kidney screening from around 11, and geriatric comfort and mobility care from 15.
That is why the number matters beyond curiosity: a cat that crosses into senior is due a different vet schedule. Most vets recommend twice-yearly check-ups from the senior stage, while a healthy prime-age cat usually manages with an annual visit.
Why “multiply by 7” is wrong for cats too
The ×7 rule makes a 1-year-old cat a 7-year-old child, when she is actually a fertile young adult — and it makes a 20-year-old cat 140, far beyond any sensible equivalent. Cats do most of their growing up in the first two years (15 + 9 = 24 human years by age 2) and then age slowly and steadily, about 4 human years per cat year. No single multiplier can capture a curve that steep at the start and that flat afterwards.
How long do cats live?
The average cat lives about 12 to 18 years — 15-year-old cats are common, 20-year-olds are not rare, and the oldest recorded cats passed 30. Indoor cats live noticeably longer than outdoor cats on average, largely because they avoid traffic, fights and infectious disease. Breed, weight and preventive care shift the odds, but the single biggest lever an owner controls is keeping the cat at a healthy weight: obesity shortens a cat's life and brings diabetes and joint disease forward. Work out the daily food figure with the pet feeding calculator, which uses the veterinary RER × MER method, and ask your vet before changing a senior cat's diet.
Quick answers
How old is a 5-year-old cat in human years?
About 36 — 24 at age 2, plus 4 a year for the next three years. A 5-year-old cat is in its prime, roughly the human equivalent of a mid-thirties adult.
How old is a 10-year-old cat in human years?
About 56 — at the end of the mature stage. The senior stage begins around 11, which is when vets usually start recommending twice-yearly check-ups.
Is my cat a senior yet?
Senior starts at about 11 years (around 60 in human years); geriatric from 15 (about 76). The cat age calculator labels the life stage from the age you enter.
Sources
- 2021 AAHA/AAFP Feline Life Stage Guidelines — the 15-9-4 conversion and the life-stage bands. Journal of Feline Medicine and Surgery 23(3):211–233. AAHA (PDF).
- International Cat Care — cat age guidance matching the same 15 / 24 / +4 scale. See our About & Sources page for the full list.
Disclaimer: General guidance only, not veterinary advice. Age conversions are comparisons to help you plan care, not medical measurements. If your cat is unwell, losing or gaining weight unexpectedly, or ageing faster than expected, see a vet.