Cat Age Calculator
Your cat's age in human years, using the veterinary convention.
The 15-9-4 rule
Veterinary groups (AAHA and AAFP) map a cat's first year to about 15 human years, the second to 9 more, and every year after that to 4. A 5-year-old cat is therefore around 36 in human terms, and a 16-year-old cat is about 80. Unlike dogs, size barely matters; indoor cats of all breeds age at a similar rate.
Life stages
Kitten to 1 year, young adult 1 to 6, mature 7 to 10, senior 11 to 14, geriatric 15+. Cats hide illness well, so the practical use of this chart is scheduling: annual vet checks for adults become twice-yearly around 'human age 60', which is 11 in cat years.