Cat Age Calculator - Cat Years to Human Years
The Cat age calculator turns your cat's age into human-equivalent years. The first year counts as about 15 human years, the second adds about 9 (24 by age two), and each year after that adds roughly 4. Enter your cat's age to see its human age in seconds.
Human-equivalent age
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How it works
How cat years compare to human years
Cats mature quickly when young, then age more steadily. A common guide puts the first year at about 15 human years and the second at about 9 more, reaching 24 by age two.
After that, each additional cat year adds roughly 4 human years, so a 5-year-old cat is around 36 in human terms.
Why these numbers are estimates
Breed, size, diet, and lifestyle all affect how a cat ages. Indoor cats often live longer than outdoor cats, so treat the result as a friendly estimate rather than a medical fact.
For health concerns, your veterinarian remains the best source of advice about your cat's life stage.
Frequently asked questions
›How is a cat's age converted to human years?
The first year counts as about 15 human years, the second adds about 9 (24 total), then each later year adds roughly 4.
›How old is a 1-year-old cat in human years?
About 15 human years, since the first year of life is the fastest stage of aging for a cat.
›How old is a 2-year-old cat in human years?
Around 24 human years, after adding about 9 to the first year's 15.
›Is this calculation exact?
No. It is a popular estimate. Breed, size, diet, and indoor or outdoor living all change how a cat ages.
›Does the formula work for kittens under one year?
It is designed for whole years. Kittens age very fast, so use the result as a rough guide only.
About this calculator
This calculator uses published formulas and reference values from the sources listed below. Results are estimates and depend on the accuracy of your inputs; they cannot account for your individual medical history.
Important: This tool is for general information only and is not medical advice, diagnosis, or treatment. Consult a qualified healthcare professional about your health.
- Sources
- Based on widely used standard formulas. See our methodology page for how tools are built and reviewed.
- Last reviewed