How cat years are calculated
Cats compress a lot of living into their first two years: a 1-year-old cat is roughly a 15-year-old human, and a 2-year-old is about 24. From there aging slows to a steady pace of about four human years per cat year. Unlike dogs, cat aging doesn't vary much by breed size — which makes the feline formula simpler and more consistent.
Cat years to human years chart
| Cat age | Human years | Life stage |
|---|---|---|
| 6 months | ~10 | Kitten |
| 1 | 15 | Young adult |
| 2 | 24 | Young adult |
| 4 | 32 | Young adult |
| 6 | 40 | Young adult |
| 8 | 48 | Mature adult |
| 10 | 56 | Mature adult |
| 12 | 64 | Senior |
| 15 | 76 | Senior |
| 18 | 88 | Senior |
| 20 | 96 | Senior |
What your cat's life stage means
The 2021 AAHA/AAFP Feline Life Stage Guidelines divide feline life into four stages: kitten (birth–1 year), young adult (1–6), mature adult (7–10) and senior (over 10). The practical takeaway: from the mature-adult stage onward, subtle weight loss, increased thirst or behavior changes are worth a vet visit — cats are masters at hiding illness.
Frequently asked questions
How old is my cat in human years?
A cat reaches roughly 15 human years in its first year, 24 by age two, and gains about 4 human years for every cat year after that. A 10-year-old cat is about 56 in human years.
Do indoor and outdoor cats age differently?
The aging formula is the same, but outdoor cats face far more risk — traffic, fights, parasites and disease — so their average lifespan is dramatically shorter (often 2-5 years vs 12-18 for indoor cats).
When is a cat considered a senior?
The 2021 AAHA/AAFP Feline Life Stage Guidelines define four stages: kitten (birth to 1 year), young adult (1-6), mature adult (7-10), and senior (over 10). From the senior stage, twice-yearly checkups are recommended.
What is the oldest cat ever recorded?
Creme Puff of Austin, Texas lived 38 years and 3 days — roughly 168 in human years by this formula.