Cat Age Calculator: Cat Years to Human Years
Convert your cat's age in years and months to human years with the AAHA and AAFP style rule: 15 at one year, 24 at two, then 4 for each year after. Works for kittens and senior cats.
Enter the age in years and months to see it in human years.
About the Cat Age Calculator
The Cat Age Calculator turns your cat's age into human years. Type the age in years and months and the human age appears at once. It follows the rule used in the AAHA and AAFP feline life-stage guidance: a cat is about 15 in human years on its first birthday, about 24 on its second, and then ages about 4 human years for every year after that. A 10-year-old cat is therefore about 56, and a 16-year-old about 80. The result is an estimate, not a health assessment; individual cats age at their own pace.
Cats vary much less in size than dogs, so one rule covers every breed, from a small Singapura to a large Maine Coon. For dogs, where size matters a great deal, switch Pet to Dog to use the Dog Age Calculator with its size chart.
How to use it
Steps
- Make sure Pet is set to Cat.
- Type the Years and Months. Either can be left empty, which counts as zero.
- Read the human age. Kittens under a year get a note that the figure is approximate, because they grow so fast.
The rule
For a cat of age years from two upwards,
Under two years the calculator draws straight lines from birth to 15 at one year, and from 15 to 24 at two years. So a cat of 6 months is 7.5, and a cat of 1 year and 6 months is .
Life stages
The guidance groups cats into stages. Kittens are up to one year old. Young adults are one to six, roughly 15 to 40 in human years. Mature adults are seven to ten, and seniors are ten and older, which is the mid-fifties and beyond in human years. Older cats benefit from regular check-ups, because they hide pain and illness well. Changes in appetite, thirst, weight or grooming are worth mentioning to your vet at any age. Use the Days Until Calculator to count down to your cat's next birthday or its next vet visit.
Worked examples
- A 2-year-old cat: 24 human years.
- A 10-year-old cat: .
- A 16-year-old cat: .
Privacy
Nothing is uploaded; every calculation runs in your browser and never leaves your device. The ages you type stay on this page and are gone when you close or reload it.
Frequently asked questions
How old is my cat in human years?
A one-year-old cat is about 15 in human years and a two-year-old about 24. Each year after that adds about 4, so a 10-year-old cat is about 56 and a 16-year-old about 80.
Why is the first year worth 15 human years?
Kittens grow and mature very quickly. By their first birthday most cats are fully grown and sexually mature, much like a person in their mid-teens.
When is a cat a senior?
The AAHA and AAFP life-stage guidance calls cats from about 10 years seniors, which is in the mid-fifties in human years. Senior cats benefit from more regular vet check-ups.
Does the breed of my cat change the result?
Not in this calculator. Cats vary far less in size than dogs, so one rule is used for every cat. Individual cats still age differently, so the result is an estimate.
How does it handle months?
Enter years and months. Under two years the calculator interpolates in a straight line, so a cat of 1 year and 6 months is 19.5 in human years.