How to use the cat age calculator
- Enter your cat’s age in years, plus any extra months.
- Read the age in human years and its life stage.
Cats of different breeds and sizes age at much the same rate, so unlike the dog age calculator there is no size setting.
The formula
The calculator follows the age chart published by the American Animal Hospital Association (AAHA) with its life stage guidelines:
- 6 months = 10 human years
- 1 year = 15
- 2 years = 24
- every year after that adds 4: 3 = 28, 4 = 32, 10 = 56, 15 = 76, 20 = 96, 21 = 100
Between the chart points the calculator moves in a straight line, so 18 months is 19.5 (shown as 20). Kittens younger than 6 months are scaled from 0 to 10.
Life stages come from the 2021 AAHA/AAFP Feline Life Stage Guidelines: kitten (birth to 1 year), young adult (1 to 6), mature adult (7 to 10) and senior (10 and older). A cat at any age can be at the end of life if it is very ill.
Tips
- Vet visits by stage. The AAHA/AAFP guidelines suggest at least a yearly exam for kittens, young adults and mature adults, and every six months for seniors.
- Watch the weight. Middle-aged cats often gain weight, and older cats may lose it. The cat weight calculator helps you check.
- Adjust food with age. Calorie needs change with life stage; see the cat food calculator.
Sources
- American Animal Hospital Association: canine and feline age chart (AAHA life stage guidelines).
- Quimby J. et al. (2021). 2021 AAHA/AAFP Feline Life Stage Guidelines. Journal of Feline Medicine and Surgery 23: 211–233.
- O’Neill D.G. et al. (2015). Longevity and mortality of cats attending primary care veterinary practices in England. Journal of Feline Medicine and Surgery 17: 125–133.
Frequently asked questions
How old is my cat in human years if he is 3?
28. On the AAHA chart a cat is 15 at one year, 24 at two, and then adds 4 human years for every year after that, so a 3-year-old cat is 28.
How many human years is 1 cat year?
The first year counts as 15 human years and the second as about 9 more. After the age of two, each cat year adds about 4 human years.
How are cat years calculated?
Vets use a chart rather than a single multiplier, because cats grow up very fast in their first two years and then age more slowly. The AAHA chart starts at 10 for a 6-month-old kitten, 15 at one year and 24 at two, then adds 4 per year, reaching 100 at 21.
At what age is a cat considered a senior?
The 2021 AAHA/AAFP Feline Life Stage Guidelines call cats seniors from 10 years old. Before that, they are kittens to 1 year, young adults from 1 to 6 years and mature adults from 7 to 10.
How long do indoor cats live?
A study of cats seen by vets in England (O’Neill et al., 2015) found a median lifespan of 14.0 years, with crossbred cats living longer than purebreds. Keeping cats indoors protects them from traffic and fights, but that study did not split indoor and outdoor cats.