How it works
Cats grow up fast. By their first birthday they are roughly equivalent to a 15-year-old person, and by two about 24. After that, each cat year is about four human years.
Life stages follow the 2021 AAHA/AAFP Feline Life Stage Guidelines: kitten (birth to 1 year), young adult (1–6), mature adult (7–10) and senior (over 10).
Formula
Year 1 = 15, year 2 = 24, then +4 per year
Questions people ask
How long do cats live?
Indoor cats commonly live 12 to 18 years, and some reach their 20s. Outdoor cats tend to have shorter lives because of traffic, disease and predators.
When is a cat a senior?
The AAHA/AAFP guidelines call cats over 10 seniors. Twice-yearly vet checkups are often recommended from then on.
Does breed affect cat aging?
Much less than in dogs, since cats vary far less in size. Some breeds have known health conditions, but the same age chart is generally used for all cats.