Cat Age Calculator (Cat Years to Human Years)
Convert your cat's age to human years with the veterinary chart behind the AAHA/AAFP feline life-stage guidelines: 15 at one year, 24 at two, then 4 human years per cat year. Shows the life stage (kitten, young adult, mature adult, senior). Accepts months or weeks for kittens.
Last updated: October 2026
Human-equivalent age
36 human years
Formula below · 3 sources (catvets.com, vet.cornell.edu, avma.org) · Updated Oct 2026
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About this calculator
Cats mature very quickly and then age at a steady pace, so the conversion is a short curve rather than a fixed ratio. The chart used in feline practice, and reproduced in the AAHA/AAFP feline life-stage guidelines and by Cornell's Feline Health Center, runs:
• First year: about 15 human years (a 1-year-old cat is roughly a 15-year-old adolescent: fully grown, sexually mature, still filling out). • Second year: about 9 more, so a 2-year-old cat is about 24. • Every year after that: about 4 human years. A 5-year-old cat is 36, a 10-year-old 56, a 15-year-old 76, a 20-year-old 96.
Formula: human age = 15 × age (under 1 year); 15 + 9 × (age − 1) (1 to 2 years); 24 + 4 × (age − 2) (over 2 years). Enter months or weeks for a kitten and the calculator converts.
Life stages. The 2021 AAHA/AAFP guidelines divide a cat's life into kitten (birth to 1 year), young adult (1 to 6 years), mature adult (7 to 10 years) and senior (10 years and older), and recommend check-ups at least yearly for young adults and every six months from the mature-adult stage, with blood pressure, kidney and thyroid screening for seniors. The interpretation band below the result shows the stage for the age you entered.
Unlike dogs, size and breed change the picture only a little: most cats weigh 3.5 to 5.5 kg and the usual lifespan is 13 to 17 years, with indoor cats commonly reaching 18 to 20 (about 88 to 96 in human terms). The result is a guide to where your cat is in life, not a health assessment; talk to your veterinarian about the screening that suits your cat's age.
Cat years to human years with the AAHA/AAFP life stage
Scroll sideways to see all columns →
| Cat's age | Human years | Life stage |
|---|---|---|
| 6 months | 8 | Kitten |
| 1 years | 15 | Young adult |
| 2 years | 24 | Young adult |
| 3 years | 28 | Young adult |
| 4 years | 32 | Young adult |
| 5 years | 36 | Young adult |
| 6 years | 40 | Young adult |
| 7 years | 44 | Mature adult |
| 8 years | 48 | Mature adult |
| 10 years | 56 | Mature adult |
| 12 years | 64 | Senior |
| 14 years | 72 | Senior |
| 15 years | 76 | Senior |
| 16 years | 80 | Senior |
| 18 years | 88 | Senior |
| 20 years | 96 | Senior |
| 21 years | 100 | Senior |
| 25 years | 116 | Senior |
How to use
Enter the cat's age and choose years, months or weeks. Example 1 (defaults): a 5-year-old cat. 24 + (5 − 2) × 4 = 36 human years; young adult stage. Example 2: a 10-year-old cat. 24 + 8 × 4 = 56; mature adult, about to become senior. Example 3: a 6-month-old kitten. 0.5 × 15 = 7.5, so about 8 human years. Example 4: an 18-month-old cat. 15 + 0.5 × 9 = 19.5, shown as 20. Example 5: a 20-year-old cat. 24 + 18 × 4 = 96.
Frequently asked questions
How many human years is one cat year?
The first cat year is worth about 15 human years, the second about 9, and each year after that about 4. So the common 7-to-1 rule overstates the age of a young cat and understates an old one: a 15-year-old cat is about 76, not 105.
At what age is a cat a senior?
The AAHA/AAFP feline life-stage guidelines call cats senior from 10 years (about 56 in human terms), with 7 to 10 years counted as mature adults. Veterinarians usually suggest six-monthly visits and screening for kidney disease, hyperthyroidism, high blood pressure and arthritis from the senior stage.
How old is my kitten in human years?
Kittens cover the human years from birth to adolescence in 12 months: about 1 human year per month at first (a 3-month-old is roughly a 4-year-old child, a 6-month-old about 8), reaching about 15 at their first birthday. Enter the age in weeks or months to see it.
Do indoor and outdoor cats age differently?
The conversion is the same, but outdoor cats face traffic, fights, infectious disease and parasites, and their average lifespan is years shorter than an indoor cat's 13 to 17. A well-cared-for indoor cat often reaches 18 to 20, about 88 to 96 in human years.
How does the cat chart compare with the dog formula?
Dogs have a separate scale that depends on size (small dogs age slower than giant breeds), and a 2020 DNA study gave dogs a logarithmic formula. The cat chart is the veterinary life-stage chart; no equivalent DNA clock has been published for cats. See the dog age calculator for dogs.
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Sources & references
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