How to use the Cat Age
- Enter your cat's age in years and months.
- Note whether the cat lives indoors or outdoors.
- Read the human-equivalent age and life stage.
- Use the life stage to set check-up frequency and diet.
How the calculation works
The standard scale from the American Association of Feline Practitioners maps year one to about 15 human years, year two to 24, and each subsequent year to roughly four more. A cat is a kitten to six months, junior to two years, adult to six, mature to ten, senior to fourteen and geriatric beyond that. Unlike dogs, breed makes almost no difference, since a Maine Coon and a Siamese sit within a narrow weight band by comparison.
Lifestyle is the dominant variable instead. Indoor cats commonly reach 15–20 years, while outdoor cats average considerably less because of traffic, predation and infectious disease. Chronic kidney disease, hyperthyroidism and dental disease account for most late-life feline morbidity, and all three respond well to early detection — which is why twice-yearly examinations with bloodwork are advised from around age ten.
Year 1 = 15, year 2 = 24, then +4 human years per cat yearSource: AAFP/AAHA feline life stage guidelines age conversion scale.
Worked example
An indoor cat aged 13.
- First two years = 24.
- Remaining 11 years × 4 = 44.
- Total = 68 human years.
- Life stage: senior, approaching geriatric at 14.
About 68 human years — senior, and due for twice-yearly checks with kidney and thyroid bloodwork.
Frequently asked questions
Do indoor cats live longer?+
Substantially. Indoor cats commonly reach 15–20 years; outdoor averages are far lower.
Does breed change the calculation?+
Very little. Feline size variation is small compared with dogs.
When is a cat senior?+
From about eleven years, and geriatric from fifteen under the standard life-stage scale.
What should I watch for in older cats?+
Weight loss, increased thirst and dental problems — early signs of kidney disease and hyperthyroidism.
Last reviewed August 31, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.