Cat age calculator

How cat years are calculated

The calculator uses the chart in the feline life stages handout from the Feline Veterinary Medical Association (formerly the American Association of Feline Practitioners), which co-wrote the 2021 life stage guidelines. A cat’s first year counts as 15 human years, the second brings it to 24, and every year after that adds 4: human age = 24 + 4 × (cat age − 2) from age 2 on, up to 116 at 25. For kittens the chart gives a few points along the way (1 month is like 1 year, 3 months like 4, 6 months like 10), and the calculator draws a straight line between them. Results are rounded to whole years, because the chart is a rough guide, not a measurement.

Kitten months to human years

The chart itself lists 1, 3 and 6 months; the other rows are read off the straight lines between those points. In those first 12 months a kitten goes from newborn to adult size: the chart compresses a whole human childhood and early teens into one year. The 2021 guidelines note that the window for socializing a kitten opens at 2 to 3 weeks and may be closing by 9 to 10 weeks, which is why early gentle handling matters so much.

Cat years to human years

Worked examples

• A 6-month-old kitten is about 10 in human years and still a kitten: a good age to ask your vet about neutering, vaccines and a microchip.
• A 4-year-old cat is about 32, a young adult. A yearly checkup is the minimum, with an eye on weight.
• A 12-year-old cat is about 64, a senior, so checkups every 6 months are now recommended.
• An 18-year-old cat is about 88, like a person in their late 80s.

Cats don’t age like dogs

Dogs need a size column because big dogs age faster: on the dog age calculator’s chart, a 10-year-old small dog is about 56 in human years and a 10-year-old giant dog about 78. Cats come in a much narrower range of sizes, so one line fits: a 10-year-old cat is about 56, much like a small dog. The other difference is the shape of the curve. After the first two years a cat adds a steady 4 human years each birthday, with no speeding up in old age.

The feline life stages

The 2021 AAHA/AAFP Feline Life Stage Guidelines group a cat’s life into four age-based stages and an end-of-life stage that can come at any age. Each stage shifts what a checkup looks for:

• Kitten (birth up to 1 year): vaccines, parasite control and spotting problems a cat was born with. The core vaccines take several visits, every 3 to 4 weeks until 16 to 20 weeks of age.
• Young adult (1 to 6 years): keeping weight in check: the guidelines single out obesity prevention for this stage.
• Mature adult (7 to 10 years): closer watch for early kidney disease; the task force suggests vets consider a thyroid test even in healthy-looking cats of this age.
• Senior (over 10 years): checkups at least every 6 months, and attention to weight, mobility, behavior and long-term conditions, which often come in combination.

The guidelines stress that these are convenient lines along a spectrum, not absolutes. Your vet may treat a fit 11-year-old like a mature adult.

Caring for a senior cat

Older cats are good at hiding discomfort, so small changes are worth noticing. The AVMA points out that weight loss is a bigger concern than weight gain in senior cats, and that sudden weight loss often means something is wrong, from an overactive thyroid to diabetes or kidney disease. The 2021 guidelines add that jumping and climbing less, such as giving up a favorite window seat, can be the first sign of arthritis, and that yowling at night can come from failing hearing or sight, pain, high blood pressure, an overactive thyroid or age-related confusion. A low-sided litter box, warm resting spots and food and water within easy reach make daily life easier.

How long do cats live?

Large studies of cats seen by UK vets give a realistic picture. A 2024 life-table study of 7,936 cats put life expectancy at birth at 11.7 years: 12.5 for females and 11.2 for males. Not being neutered, being purebred and being under- or overweight were all linked to shorter lives. An earlier study of 4,009 cats found a median age at death of 14 years for mixed-breed cats and 12.5 for purebreds. Outdoor life brings its own risks: in the Bristol Cats study, which followed 2,444 cats from kittenhood, road traffic accidents caused almost half the deaths before age 9. Whether your cat goes outside also changes which vaccines and parasite treatments your vet recommends.

What the number can’t tell you

A human-age equivalent helps you picture where your cat is in life, but it says nothing about how healthy your cat is. Two 12-year-old cats can be in very different shape. Use the life stage as a reminder of the care that fits, and let your vet judge the rest. If you also share your home with a dog, the dog age calculator works the same way with a size chart. For yourself, try the sleep calculator or the TDEE calculator.

Sources

• Quimby J, Gowland S, Carney HC et al. 2021 AAHA/AAFP Feline Life Stage Guidelines. Journal of Feline Medicine and Surgery, 2021.
• Stone AE, Brummet GO, Carozza EM et al. 2020 AAHA/AAFP Feline Vaccination Guidelines. Journal of Feline Medicine and Surgery, 2020.
• Feline Veterinary Medical Association. Feline life stages (client handout with the age chart). FelineVMA, 2026.
• American Veterinary Medical Association. Caring for senior cats and dogs. AVMA, accessed 2026.
• Teng KT, Brodbelt DC, Church DB, O’Neill DG. Life tables of annual life expectancy and risk factors for mortality in cats in the UK. Journal of Feline Medicine and Surgery, 2024.
• O’Neill DG, Church DB, McGreevy PD et al. Longevity and mortality of cats attending primary care veterinary practices in England. Journal of Feline Medicine and Surgery, 2015.
• Taylor AR, McDonald J, Foreman-Worsley R et al. Mortality and life table analysis in a young cohort of pet cats in the UK. Journal of Feline Medicine and Surgery, 2025.

This calculator gives an approximation, not veterinary advice. Your vet can tell you which life stage fits your cat and what checkups and care it needs.