Indoor Cat Age in Human Years — Cat Age Calculator
Convert your cat's age to human years with the AAHA/AAFP veterinary scale and see its life stage from kitten to geriatric — entirely in your browser.
Result
This page opens the cat age calculator with the indoor environment preselected. The conversion itself follows the AAHA/AAFP veterinary scale used for all cats: the first year equals about 15 human years, the second adds 9 more, and every year after that adds 4 — so a 10-year-old indoor cat is around 56 in human terms.
Living indoors does not change how a cat's body ages, but it dramatically changes how long the cat is likely to live. Indoor cats commonly reach 12–18 years and quite often 20, because they avoid the main killers of outdoor cats: traffic, predators, fights, poisoning and infectious diseases such as FeLV and FIV. That is why veterinarians overwhelmingly recommend indoor living, ideally with plenty of climbing, play and window access to keep an indoor life stimulating.
The trade-off to watch is lifestyle: indoor cats move less, and obesity is the most common nutrition problem vets see in them, which feeds into diabetes and joint disease in the mature and senior stages. Use the life-stage label this page shows — adult from 3, mature from 7, senior from 11 — as a schedule anchor: annual checkups until 7, then twice-yearly from the mature stage onward.