Cat Age Calculator

How cat years convert to human years

Cats mature very quickly. A kitten can be adolescent within a few months and is broadly grown up by its first birthday, so the first year of a cat’s life is usually counted as about 15 human years. The second year adds about 9 more, making a 2-year-old cat roughly 24. From then on, each cat year counts as about 4 human years.

This is the conversion published by International Cat Care, which lists a 2-year-old cat as 24 and adds four years for every year after that, all the way to a 25-year-old cat at 116 (International Cat Care). For kittens under a year, the calculator follows the same chart, where a 6-month-old is about 10 in human years.

Cat age chart

Your cat’s life stage

Vets often find life stages more useful than human-equivalent ages, because each stage comes with different care needs. The calculator uses the stages in the 2021 guidelines from the American Animal Hospital Association (AAHA) and the American Association of Feline Practitioners (AAFP) (AAFP):

• Kitten: birth to 1 year.
• Young adult: 1 to 6 years.
• Mature adult: 7 to 10 years.
• Senior: 10 years and older.

The guidelines also describe an end-of-life stage, which can come at any age. The boundaries aren’t strict: every cat is an individual, and a healthy 12-year-old can be livelier than an unwell 8-year-old.

International Cat Care uses six stages instead: kitten (up to 6 months), junior (7 months to 2 years), adult (3 to 6 years), mature (7 to 10), senior (11 to 14) and super senior (15 and over). Both schemes broadly agree on when a cat becomes middle-aged and old.

How long do cats live?

With good care, many cats live well into their teens, and some reach their twenties. Keeping your cat at a healthy weight, up to date with vaccinations and parasite control, and visiting the vet regularly all help. Indoor cats avoid outdoor dangers such as traffic, which is one reason they often live longer.

Not sure how old your cat is?

If you adopted an adult cat, a vet can estimate its age from clues such as its teeth (kittens have all their adult teeth by around six months old, and tartar builds up with age), its eyes, coat and muscle tone. Enter the vet’s estimate in years and months for a human-year equivalent.

Dogs age differently

Dogs follow a different curve, and their size matters much more. If you share your home with a dog too, use the dog age calculator, and read what the science says about dog years.

Last reviewed on 29 October 2026 by the Ageculator Team. See how we calculate.