Cat Age in Human Years
Convert your cat's age to human years using the standard veterinary age-equivalence scale.
| Cat years | Human years |
|---|---|
| 1 | 15 |
| 2 | 24 |
| 5 | 36 |
| 10 | 56 |
| 15 | 76 |
| 20 | 96 |
This is the AAHA/veterinary convention, not a lab measurement of aging. Indoor cats tend to live longer than outdoor cats, so the "human year" figure is a rough guide to life stage, not a precise biological clock.
How it works
Cats don't age at a steady rate compared to us. The first year covers everything from a helpless newborn to a physically mature young adult, so it counts for about 15 human years. The second year adds another 9, since a 2 year old cat is roughly equivalent to a 24 year old person, socially and physically mature but still young. After that, each additional cat year adds about 4 human years, a much slower pace than the first two.
Worked example: a cat that just turned 2 is about 24 human years old. By age 10, using the 24-plus-4-per-year rule for the 8 years past the second birthday, that same cat is about 56 human years, solidly middle-aged. A 6 month old kitten (0.5 cat years) comes out to about 8 human years old, still very much a baby.
FAQ
Why does the first year count for so much?
Cats reach physical and reproductive maturity within their first year, something that takes humans well over a decade. The 15-year jump reflects that compressed development, not a literal one-to-one aging rate.
Does this account for breed or indoor vs. outdoor life?
No. This is a general veterinary convention, and actual life expectancy varies a lot by breed, body condition, and whether a cat lives indoors or roams outside. An indoor cat typically lives longer than the "human years" table implies.
At what age is a cat considered a senior?
Most vets start using the term "senior" around 10 to 11 years, which lines up with the table here at roughly 56 to 60 human years. Some cats show age-related changes earlier or later than that, so watch your own cat's behavior and body condition rather than just the calendar.
Should I change how I feed my cat as they age?
Yes, energy needs and health risks shift with age. Kittens need far more calories per pound than adults, and senior cats often need diet adjustments for kidney health, weight, or dental issues. Ask your vet before changing an older cat's diet.
Related reading: senior cat care, what changes with age and how feeding needs change from kitten to senior.