Dog Age
Calculator
Dog years to human years.
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Pets
Cat Age Calculator
Convert your cat’s age to human years and see its life stage.
Human age
—
In human years.
| Life stage | — |
|---|---|
| Ageing rate now | — |
| Cat’s age | — |
| Rule | — |
Show our math
Enter your figures above to see the step-by-step working.
A friendly estimate — ask your vetEverything computed client-side — nothing leaves this page
How the Cat Age Calculator Works
Cats grow up quickly, then age steadily. The standard veterinary conversion counts a cat’s first year as about 15 human years and the second as another 9 — so a two-year-old cat is roughly 24 in human terms — then adds about 4 human years for every cat year after that.
By this reckoning an indoor cat of 15 is around 76 in human years. Vets group cats into life stages — kitten, young adult, mature, senior and geriatric — which help guide diet and check-up frequency as your cat gets older.
human age = 15 (year 1) + 9 (year 2) + (age − 2) × 4
Note: a friendly estimate based on common averages. Breeds vary widely — your veterinarian knows your pet best.
Frequently Asked Questions
How old is my cat in human years?
The first year counts as about 15 human years, the second reaches 24, and each year after adds roughly 4. A 5-year-old cat is about 36 in human years.
What are the cat life stages?
Kitten (under 1), young adult (1–6), mature (7–10), senior (11–14) and geriatric (15+). This calculator labels the stage for your cat’s age.
Do indoor and outdoor cats age differently?
The human-year conversion is the same, but indoor cats generally live longer on average, so they more often reach the senior and geriatric stages.
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