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Cat years calculator

Enter your cat's age to see it in human years and find out which life stage your cat is in, with the full cat age chart.

By the Calcist team · Checked against known answers · Updated October 29, 2026

Private: calculated on your device. Nothing you type is sent anywhere.

Next: Have a dog as well? The dog years calculator converts by size and by DNA.

How cat years are counted

Cats grow up fast. By the chart AAHA and the AVMA use, a 6-month-old kitten is like a 10-year-old child, a 1-year-old cat like a 15-year-old, and a 2-year-old like a 24-year-old adult. After that, each cat year adds about 4 human years.

Cat age 2 or more: human years = 24 + 4 × (cat age − 2)

Worked example

A 10-year-old cat: 24 + 4 × (10 − 2) = 24 + 32 = 56 human years. That's a mature adult; by the 2021 AAHA/AAFP guidelines, she becomes a senior after 10.

Cat life stages

The 2021 AAHA/AAFP Feline Life Stage Guidelines group cats by age so vets can tailor care:

  • Kitten: birth up to 1 year
  • Young adult: 1 to 6 years
  • Mature adult: 7 to 10 years
  • Senior: over 10 years
  • End of life: can happen at any age

The guidelines recommend a vet exam at least once a year for every cat, and at least every 6 months for seniors.

Cat age chart

Cat ageHuman yearsLife stage
6 months10Kitten
1 year15Young adult
2 years24Young adult
3 years28Young adult
4 years32Young adult
5 years36Young adult
6 years40Young adult
7 years44Mature adult
8 years48Mature adult
9 years52Mature adult
10 years56Mature adult
11 years60Senior
12 years64Senior
13 years68Senior
14 years72Senior
15 years76Senior
16 years80Senior
17 years84Senior
18 years88Senior
19 years92Senior
20 years96Senior
21 years100Senior

Limits

  • The chart is a rough comparison of development, not a measure of your cat's health.
  • Indoor cats, breed and health conditions all affect how a cat ages. Your vet can tell you more about your cat.
  • For ages between rows, the calculator draws a straight line between chart values. The chart doesn't list kittens under 6 months.

Sources

How we checked this

Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:

  • 4-year-old cat: 32 human years ✓
  • 10-year-old cat: 56 human years, a mature adult ✓
  • 1 year 6 months: 19.5 human years ✓
  • 12-year-old cat is a senior ✓
  • 25 years is past the chart (edge) ✓

Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.

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Questions people ask

How old is my cat in human years?

Count 15 for the first year, 24 at age 2, then add 4 for each year after that. A 5-year-old cat is about 36, a 10-year-old about 56 and a 15-year-old about 76.

How do you calculate cat years?

For cats 2 and older: 24 + 4 × (age − 2). Under 2, use the chart: 10 at 6 months, 15 at 1 year, 24 at 2 years.

When is a cat considered a senior?

After 10 years, according to the 2021 AAHA/AAFP Feline Life Stage Guidelines. Cats 7 to 10 are mature adults.

Is one cat year seven human years?

No. Cats mature much faster in their first two years (about 24 human years by age 2), then age about 4 human years per year.

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