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Cat Years Calculator

A cat's first year is about 15 human years, the second adds 9 more to reach 24, and every year after that is about 4 human years. So a 7-year-old cat is about 44, and a 6-month-old kitten is about 10. Enter your cat's age for the human-year equivalent.

By Sikander Malik · Updated October 10, 2026 · Sources

years

About

44human years

The first year is about 15 human years, the second adds 9 more, then about 4 a year after that.

Life stageMature adult

Estimates only, not veterinary advice. Ask your vet about your pet’s health.

How to use it

  1. Enter your cat's age, switching between years and months for kittens.
  2. Read the human-year equivalent and the life stage.
  3. Use months for cats under 2, where each month counts for a lot.
Side profile of a calm green-eyed tabby cat

Photo: Engin Akyurt / Pexels

The formula, with two examples

We use International Cat Care's chart. The first year equals about 15 human years and the second reaches 24 (so year two adds 9). From age 2, each cat year is about 4 human years, so the total is 24 + 4 × (cat age − 2). We interpolate between the early anchor points for kittens.

Example 1. A 7-year-old cat: 24 + 4 × (7 − 2) = 44 human years.

Example 2. A 6-month-old kitten is about 10 human years on the chart.

What this calculator doesn’t cover

  • Breed differences in lifespan.
  • Individual health, which matters more than age alone.
  • The outdated “×7” rule, which does not fit how cats age.
Cat age in human years
Cat ageHuman years
1 month1
3 months4
6 months10
1 year15
18 months21
2 years24
3 years28
5 years36
10 years56
15 years76
20 years96
Source: International Cat Care, cat age in human years.

Tips

  • For kittens, count in months. The jump from 3 to 6 months alone is like going from 4 to 10 human years.
  • Indoor cats commonly live into their mid to late teens, so a 15-year-old cat (about 76 in human years) is not unusual.
  • Watch for senior changes from about 10 years (56 human years): weight, thirst, and activity.

Questions owners ask

How old is a 1-year-old cat in human years?
About 15 human years. A cat’s first year packs in a huge amount of development, from newborn to full adolescence. The second year adds about 9 more to reach 24 by age 2, after which aging settles to roughly 4 human years per cat year.
Do cats age faster than dogs?
Early on they age similarly, and both reach about 24 human years by age 2. After that, cats age at a fairly steady 4 human years per year, while large dogs age faster than small dogs. Small dogs and cats end up on a similar long-lived curve.
When is a cat a senior?
The 2021 feline life stage guidelines treat cats as mature adults from about 7 years and senior from about 10 to 11 years (roughly 56 to 60 in human years). Senior cats benefit from more frequent vet checks and attention to weight and kidney health.
How long do indoor cats live?
Many indoor cats live into their mid to late teens, and some reach their early 20s. A 20-year-old cat is about 96 in human years on this chart. Lifespan depends on genetics, weight, dental care and veterinary care.
How old is a 15-year-old cat?
About 76 human years. At this age a cat is a senior and may show changes in weight, appetite, thirst, grooming or activity. Twice-yearly vet visits help catch age-related conditions like kidney disease and arthritis early.
How do vets estimate a cat’s age?
For cats of unknown age, vets look at teeth (eruption and wear), eye clarity, coat condition and muscle tone. These give a range rather than an exact age. For kittens, body weight and development are the most useful clues.

Related tools

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Dog years calculator

Sources

Estimates only, not veterinary advice. Ask your vet about your pet’s health.