Pet Care Calculators
Cat Age Calculator: Cat Years to Human Years
Curious how old your cat is in human terms? This cat age calculator converts your cat's age into human years using the widely accepted feline method and tells you which life stage your cat is in — from kitten to geriatric — so you can tailor care as they age.
Last reviewed: June 2026
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Your result will appear here after you press Calculate.
A general guide only. Indoor cats often live longer than the averages suggest.
Formula used
The calculator uses the standard feline life-stage method:
- Year 1 ≈ 15 human years
- Year 2 ≈ 24 human years (year two adds about 9)
- Each year after that adds about 4 human years
Worked examples
5-year-old cat
A 5-year-old cat is about 36 human years old — 24 for the first two years plus 12 for the next three. This is a cat in its prime adult years.
15-year-old cat
A 15-year-old cat is about 76 human years old and is considered geriatric, benefiting from more frequent vet check-ups.
How to use this calculator
- Enter your cat's age in years (use a decimal such as 0.5 for a 6-month-old kitten).
- Press Calculate to see the human-age equivalent.
- Check the life stage to guide diet, play, and veterinary care.
Reference chart
| Cat age | Human years | Life stage |
|---|---|---|
| 6 months | 10 | Kitten |
| 1 yr | 15 | Junior |
| 2 yr | 24 | Junior |
| 5 yr | 36 | Adult (prime) |
| 10 yr | 56 | Mature |
| 14 yr | 72 | Senior |
| 18 yr | 88 | Geriatric |
Frequently asked questions
How old is my cat in human years?
A common method is: the first year of a cat's life equals about 15 human years, the second year brings the total to about 24, and each year after that adds roughly 4 human years. Enter your cat's age above for the exact figure.
How old is a 1-year-old cat in human years?
About 15 human years. A one-year-old cat has reached adult size and behaves much like a human teenager — energetic and curious but newly mature.
When is a cat considered a senior?
Cats are usually considered mature from about 7 years, senior from around 11, and geriatric from 15. Senior cats benefit from twice-yearly vet visits, joint-friendly access to favorite spots, and diet adjustments.
Do indoor cats age differently from outdoor cats?
The age-conversion math is the same, but indoor cats typically live longer and more safely, often reaching their late teens or older. Outdoor cats face more hazards, so their effective lifespan is usually shorter.
How do I calculate my kitten's age in human years?
Enter the age as a decimal, such as 0.25 for three months or 0.5 for six months. Kittens develop very quickly — a six-month-old kitten is roughly equivalent to a 10-year-old child.
Is the cat age calculation exact?
It's a well-established estimate, not a precise measurement. Breed, genetics, weight, and health all influence how a cat ages. Use the result as a helpful guide rather than a medical figure.