Cat Age Calculator
Turn your cat’s age into human years with the standard feline curve — a fast first two years, then about four human years each year after.
How it works
human years = 15 (year 1) + 9 (year 2) + 4 × (age − 2)
Cats grow up quickly and then age at a fairly even pace. The first year is worth roughly 15 human years and the second adds about 9 (reaching 24), and from then on each cat year is worth about 4 human years. Unlike dogs, size barely changes the feline curve, so one formula covers most cats.
Worked example
A 5-year-old cat: 15 for year one, +9 for year two (24), then +4 for years three, four and five — 24 + 12 = about 36 human years, a cat in its prime.
Frequently asked questions
Do indoor and outdoor cats age the same?
The conversion curve is the same, but indoor cats commonly live longer in practice — often into their late teens — because they face fewer hazards.
When is a cat a “senior”?
Vets generally call cats seniors around 11 human-equivalent-60s, i.e. about 10–11 calendar years. Geriatric care often starts around 15 calendar years.
Why isn’t it just seven years per year?
Because kittens mature far faster than that early on, then slow down. A flat multiplier badly overstates a young cat and understates the first two years.
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This calculator is for educational purposes. Double-check important results before acting on them.