Cat Age Calculator: Cat Years to Human Years

Cats mature quickly in their first two years and then age at a steadier pace. The calculator uses the chart published by International Cat Care, a cat-welfare charity, and adds the cat’s life stage as defined by the American Association of Feline Practitioners (AAFP) and the American Animal Hospital Association (AAHA).

How the chart works

The International Cat Care chart is built from a few simple steps:

• First month: about 1 human year.
• Months 2 to 7: about 2 human years per month (2 months = 2, 3 months = 4… 7 months = 12).
• 7 months to 2 years: 12 months = 15, 18 months = 21, 2 years = 24.
• From 2 years on: +4 human years per cat year (3 years = 28, 4 = 32… 25 = 116).

For ages between the listed points, the calculator draws a straight line between the two nearest values. The AVMA’s “Pets age faster than people” poster uses the same values for cats from 1 year on (15, 24, 28, 32…).

Cat age	Human years	Cat age	Human years
1 month	1	8 years	48
3 months	4	9 years	52
6 months	10	10 years	56
7 months	12	11 years	60
1 year	15	12 years	64
18 months	21	13 years	68
2 years	24	14 years	72
3 years	28	15 years	76
4 years	32	16 years	80
5 years	36	18 years	88
6 years	40	20 years	96
7 years	44	25 years	116

Source: International Cat Care, “How to tell your cat’s age in human years.”

Life stages: AAFP/AAHA 2021

The 2021 Feline Life Stage Guidelines group cats by what their care should focus on, not by human-year equivalents:

Life stage	Age
Kitten	Birth up to 1 year
Young adult	1 to 6 years
Mature adult	7 to 10 years
Senior	10 years and older

The guidelines also describe an “end-of-life” stage, which can happen at any age, so the calculator doesn’t assign it. Because the guidelines’ age bands meet at whole years, the calculator switches stage on the birthday: a cat becomes a mature adult on its 7th birthday and a senior on its 10th.

International Cat Care uses slightly different names (kitten, junior, adult, mature, senior, super senior). Both systems agree that cats over about 10 benefit from closer attention.

Worked examples

Example 1: a 5-year-old cat. Read the chart at 5 years → 36 human years. Life stage: young adult.

Example 2: a 9-month-old kitten. Between 7 months (12) and 12 months (15). Nine months is 2 of those 5 months along, so 12 + 3 × 2/5 = 13.2 human years. Life stage: kitten.

Example 3: a 14-year-old cat. Chart → 72 human years. Life stage: senior.

Example 4: a 2½-year-old cat. Between 24 (2 years) and 28 (3 years), halfway → 26 human years.

Limitations

• The chart is a convention for comparing life stages. International Cat Care doesn’t explain how each value was derived, and the number says nothing about your cat’s health.
• Individual cats age differently. Indoor and outdoor lifestyle, weight and chronic disease all matter more than the number.
• The values stop at 25 years. Cats older than that are rare but exist.
• If you’re unsure how old your cat is, your veterinarian can give an approximate age.