Cat Age Calculator
Convert cat years to human years with the standard veterinary formula, plus your cat's life stage and breed life expectancy.
Last reviewed July 2026 · Free · Nothing you enter is stored
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Educational estimate. Cats age fairly uniformly across breeds; your vet is the best judge of your cat's health stage.
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The formula, and why the first two years are different
A kitten reaches sexual maturity somewhere between five and nine months and full adult size before its first birthday. Nothing in human development is compressed that hard, which is why the conversion cannot be a straight multiplication. The veterinary convention handles it by treating year one as worth about 15 human years and year two as worth another 9, after which the curve settles into a steady 4 human years per cat year.
That gives a set of landmarks worth remembering: a one-year-old cat is a teenager, a two-year-old is in its mid-twenties, a seven-year-old is pushing 45, and a fifteen-year-old is in its late seventies. The oldest reliably documented cat, Creme Puff, reached 38 — well past 160 by this arithmetic.
Life stages and what changes at each
| Stage | Cat age | Human equivalent | What matters |
|---|---|---|---|
| Kitten | 0–6 months | 0–10 human years | Growth, socialisation, vaccine series, spay or neuter. |
| Junior | 7 months–2 years | 12–24 human years | Full size reached; energy peaks; the age most cats are surrendered. |
| Prime adult | 3–6 years | 28–40 human years | Healthiest stretch. Annual exams, watch body weight. |
| Mature | 7–10 years | 44–56 human years | Weight gain and early dental disease typically show up here. |
| Senior | 11–14 years | 60–72 human years | Twice-yearly exams. Screen for kidney disease and hyperthyroidism. |
| Geriatric | 15+ years | 76+ human years | Arthritis, weight loss, and chronic kidney disease become common. |
The transition worth planning for is mature to senior, around eleven. Three conditions — chronic kidney disease, hyperthyroidism, and dental disease — account for a large share of what shortens cats' lives, all three are common past ten, and all three are far more manageable when caught on routine bloodwork than when caught on symptoms. Cats hide illness well; by the time a cat looks unwell it has usually been unwell for a while.
Indoor versus outdoor
Published life expectancy figures for indoor cats cluster around 12 to 18 years. Estimates for cats with free outdoor access run substantially lower, and the causes are almost entirely external: vehicles, other animals, and transmissible disease such as FIV and FeLV. Compromises like catios, harness walks, and supervised time outside capture most of the enrichment benefit without the mortality. Indoor cats do need deliberate enrichment — vertical space, puzzle feeders, and play — because obesity and boredom-related problems are their own risk.
Life expectancy by breed
Breed does not change how fast a cat ages, but it does change how long the average individual lives and how big it gets. All 36 breeds in our data:
| Breed | Adult weight (lbs) | Life expectancy (yrs) |
|---|---|---|
| Abyssinian | 6–10 | 12–15 |
| American Curl | 5–10 | 12–16 |
| American Shorthair | 8–15 | 15–20 |
| Balinese | 5–10 | 12–20 |
| Bengal | 8–15 | 12–16 |
| Birman | 6–12 | 12–16 |
| British Shorthair | 7–17 | 12–17 |
| Burmese | 6–12 | 16–18 |
| Chartreux | 7–16 | 11–15 |
| Cornish Rex | 6–10 | 11–15 |
| Devon Rex | 6–9 | 9–15 |
| Domestic Longhair | 8–15 | 12–18 |
| Domestic Shorthair | 8–12 | 12–18 |
| Egyptian Mau | 6–14 | 12–15 |
| Exotic Shorthair | 7–12 | 12–15 |
| Himalayan | 7–12 | 9–15 |
| Maine Coon | 10–25 | 12–15 |
| Manx | 8–12 | 11–13 |
| Munchkin | 5–9 | 12–15 |
| Norwegian Forest Cat | 9–16 | 14–16 |
| Ocicat | 6–15 | 12–15 |
| Oriental Shorthair | 8–12 | 12–15 |
| Persian | 7–12 | 10–17 |
| Ragamuffin | 8–20 | 12–16 |
| Ragdoll | 10–20 | 12–17 |
| Russian Blue | 7–12 | 15–20 |
| Savannah | 12–25 | 12–20 |
| Scottish Fold | 6–13 | 11–15 |
| Selkirk Rex | 6–16 | 10–15 |
| Siamese | 6–14 | 15–20 |
| Siberian | 8–17 | 11–18 |
| Singapura | 4–8 | 11–15 |
| Somali | 6–10 | 12–16 |
| Sphynx | 6–12 | 9–15 |
| Tonkinese | 6–12 | 12–16 |
| Turkish Angora | 5–9 | 12–18 |
Ranges follow CFA and TICA breed standards and established veterinary references. Mixed-breed domestic shorthairs and longhairs sit near the middle and often at the top of it.
Frequently asked questions
How do you convert cat years to human years?
The veterinary convention: a cat's first year equals about 15 human years, the second year adds 9 more (so a two-year-old cat is roughly 24), and every year after that adds about 4 human years. A ten-year-old cat comes out around 56 in human terms. The front-loading matters — a one-year-old cat is not a child, it is a fully grown adult that can already reproduce.
How long do indoor cats live?
Indoor cats commonly live 12 to 18 years, and reaching the early twenties is not unusual. Outdoor and indoor-outdoor cats average considerably less, largely because of traffic, predators, fights, and infectious disease rather than any difference in how they age. The gap in published estimates is wide, but every study points the same direction.
When is a cat considered senior?
The American Association of Feline Practitioners places cats as mature at 7 to 10, senior at 11 to 14, and geriatric at 15 and up. The practical change at 'senior' is frequency: twice-yearly exams with bloodwork, because chronic kidney disease, hyperthyroidism, and dental disease all develop silently and all respond much better to early treatment.
Why doesn't breed change the conversion?
Because cats age remarkably uniformly compared with dogs. There is nothing in the cat world resembling the gap between a Chihuahua and a Great Dane — domestic cats span roughly 6 to 20 lbs, and that range is too narrow to shift the aging curve. What breed does change is life expectancy and adult size, which is what the breed dropdown here adds to your result.
How can I tell a cat's age if I don't know it?
A vet estimates from teeth, eyes, and coat. Kittens get their permanent teeth by about seven months; tartar builds from two to five years; noticeable wear and yellowing suggests five to ten. The iris loses smoothness and the lens clouds slightly with age, and older cats develop coarser, sometimes matted coats as grooming gets harder. None of this is precise, but a good exam usually places an adult cat within a two- to three-year window.
Does my cat's age change how much I should feed it?
Yes. Energy needs drop as cats move from kitten to neutered adult, and then rise again in many cats after about eleven as digestive efficiency declines — one of the few species where senior animals may need more calories, not fewer. Our cat food calculator applies the life-stage multipliers directly.
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