Cat Age Calculator

Quick answer A 1-year-old cat is about 15 in human years, a 2-year-old about 24, and each year after adds about 4, so a 10-year-old cat is roughly 56. Life stages follow AAFP/AAHA guidelines: kitten under 1, young adult 1–6, mature adult 7–10, senior over 10. Treat the result as an estimate; every cat ages differently.

How to use the cat age calculator

Enter your cat's age in months or years.
Press Calculate.

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Worked example

A 10-year-old cat.

Cat's age (in the unit chosen below): 10
Unit: Years

56 human years

Life stage (AAFP/AAHA): Mature adult

Example values are illustrative; this result is produced by the same calculator above.

How we calculate it

Year 1 = 15, year 2 = 24, then +4 per year; life stages: kitten <1, young adult 1–6, mature 7–10, senior >10

Sources: AAFP/AAHA · Vogt A.H. et al. · Teng K.T. et al.

Reference table

Cat age in human years (AAFP/AAHA)
Cat age	Human years
6 months	10
1 year	15
2 years	24
5 years	36
10 years	56
15 years	76
20 years	96

Understanding your result

A cat's first year equals about 15 human years and its second year takes it to about 24. After that each cat year adds about 4 human years. A 10-year-old cat is therefore around 56.

For kittens under one year the tool uses a month-by-month table from the AAFP and AAHA life stage guidelines.

The tool also gives the life stage (kitten, young adult, mature adult, senior), which is more useful than the human-year number for deciding on diet and check-ups.

Common mistakes

Entering age in months while the unit is set to years, or the other way round.
Taking the human age literally for health decisions.
Assuming indoor and outdoor cats age differently without evidence.

Good to know

Cats over about 10 years are usually considered senior, and regular check-ups are recommended.
Many cats live into their teens.
Your vet can advise on diet and tests that suit your cat's age.

Frequently asked questions

How old is my cat in human years?

About 15 at one year, 24 at two, then roughly 4 human years for each year after.

When is a cat a senior?

AAFP/AAHA guidelines call cats over about 10 years senior; regular senior check-ups are recommended.

How long do cats live?

Many cats live into their teens; a large UK study (Teng et al., 2024) found an average life expectancy at birth of about 11.7 years.

What are the cat life stages?

Under 1 year is a kitten, 1–6 is a young adult, 7–10 is a mature adult and over 10 is a senior, following AAFP/AAHA life stage guidelines. The stages help you plan check-ups, diet and home changes as your cat gets older.

Is a 15-year-old cat very old?

A 15-year-old cat is about 76 in human years on this scale (24 at year two plus about 4 for each year after). That is firmly in the senior stage, so regular senior check-ups with your vet are recommended.

Why not just multiply a cat's age by seven?

Cats mature very quickly in their first two years and then age more slowly, so a flat multiplier gets young and middle-aged cats wrong. This calculator uses 15 for year one, 24 for year two and about 4 for each year after that.

Reviewed by a licensed veterinarian

Last reviewed 18 Oct 2026 · How we review

Sources

Guides about this

Cat Years to Human Years: Age Chart (Kitten to 20)A clear cat age chart from kitten to 20 years, how the AAFP/AAHA scale works, the cat life stages and how long cats usually live.

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