DogYearsCat age calculator
Cats are not small dogs, but their ageing curve starts the same way: a one-year-old cat is about 15 in human terms, a two-year-old about 24, and from there each year adds roughly four.
Life stage: Adult
Cat years to human years chart
| Cat age | Human years |
|---|---|
| 1 yr | 15 |
| 2 yr | 24 |
| 3 yr | 28 |
| 4 yr | 32 |
| 5 yr | 36 |
| 6 yr | 40 |
| 7 yr | 44 |
| 8 yr | 48 |
| 9 yr | 52 |
| 10 yr | 56 |
| 11 yr | 60 |
| 12 yr | 64 |
| 13 yr | 68 |
| 14 yr | 72 |
| 15 yr | 76 |
| 16 yr | 80 |
| 17 yr | 84 |
| 18 yr | 88 |
| 19 yr | 92 |
| 20 yr | 96 |
Why the curve bends. Kittens develop astonishingly fast — most are fully grown and reproductively mature well before their first birthday, which is why year one maps to about 15 human years rather than 7. After the second year, feline ageing settles into a steadier rhythm of roughly four human years per cat year, and unlike dogs there is no widely used size adjustment, since domestic cats vary far less in adult size.
As with the dog numbers, treat these as comparison estimates, not a health assessment. Whether your cat needs senior screening, diet changes or extra monitoring is a conversation for your vet, who knows the individual animal.
Cat questions
How old is a 5-year-old cat in human years?
About 36. Cats follow the same opening curve as dogs — 15 human years for year one, 24 by year two — and then add roughly 4 human years per year after that, so a 5-year-old cat is 24 + (3 × 4) = 36.
Do indoor and outdoor cats age differently?
The conversion curve is the same, but typical lifespan differs: indoor cats commonly live 12–18 years, while outdoor cats often live shorter lives on average due to accidents, disease and predators. The chart describes ageing pace, not life expectancy.
When is a cat considered senior?
Commonly from about 10–11 years — roughly 56–60 in human years — with many vets suggesting twice-yearly check-ups from around that age. As with dogs, your vet may adjust based on your cat's health rather than the calendar alone.