Cat Years to Human Years Calculator
Enter the age of your cat and see how old it is in human years. The first year counts as 15 human years, the second adds 9 and every year after that adds 4.
Your cat in human years
Cat years to human years chart
| Age of the cat | In human years | Life stage |
|---|---|---|
| 1 year | 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 |
| 9 years | 52 | Mature adult |
| 10 years | 56 | Mature adult |
| 11 years | 60 | Senior |
| 12 years | 64 | Senior |
| 13 years | 68 | Senior |
| 14 years | 72 | Senior |
| 15 years | 76 | Senior |
| 16 years | 80 | Senior |
| 17 years | 84 | Senior |
| 18 years | 88 | Senior |
| 19 years | 92 | Senior |
| 20 years | 96 | Senior |
| 21 years | 100 | Senior |
Human years to cat years
The same rule read backwards: how old is a cat that matches a human of a given age?
| Human age | Age of the cat |
|---|---|
| 15 years | 1 year |
| 24 years | 2 years |
| 30 years | 3.5 years |
| 40 years | 6 years |
| 50 years | 8.5 years |
| 60 years | 11 years |
| 70 years | 13.5 years |
| 80 years | 16 years |
| 90 years | 18.5 years |
| 100 years | 21 years |
How the conversion works
up to 1 year: human years = cat years × 15 1 to 2 years: human years = 15 + (cat years − 1) × 9 more than 2: human years = 24 + (cat years − 2) × 4
Example: a cat of 7 years: 24 + (7 − 2) × 4 = 44 human years. A cat of 12 years: 24 + 10 × 4 = 64.
In its first year a kitten goes from newborn to fully grown. The calculator spreads those 15 human years evenly over the twelve months, which is a simplification: a 6-month-old kitten comes out at 8.
Why not multiply by seven?
The rule of seven assumes that cats age at the same speed all their lives. They do not. A cat is fully grown after one year, which seven human years does not describe. After the second year the pace slows to about four human years per year. The rule of seven is too low for young cats and far too high for old ones: it turns a 20-year-old cat into a 140-year-old.
Cat life stages
Veterinary guidelines divide the life of a cat into four stages. They are the stages shown in the calculator and the chart.
| Life stage | Age of the cat | In human years |
|---|---|---|
| Kitten | Birth up to 1 year | Up to 15 |
| Young adult | 1 to 6 years | 15 to 40 |
| Mature adult | 7 to 10 years | 44 to 56 |
| Senior | Over 10 years | 60 and older |
Cat Years to Human Years Calculator: Questions and Answers
- How old is a 15-year-old cat in human years?About 76. The first two years count as 24 human years, and the 13 years after that add 4 each: 24 + 13 × 4 = 76.
- How old is an 18-year-old cat in human years?About 88: 24 for the first two years plus 16 × 4 for the years after.
- How old is a 20-year-old cat in human years?About 96: 24 for the first two years plus 18 × 4 for the years after.
- How old is a 2-year-old cat in human years?About 24. The first year counts as 15 human years and the second adds 9.
- How many cat years are in one human year?It depends on the age of the cat. Its first calendar year counts as 15 human years, the second as 9, and every year after that as 4.
- How do I convert human years to cat years?Run the rule backwards. Up to 15 human years, divide by 15. From 15 to 24, the cat is between 1 and 2. Above 24, subtract 24, divide by 4 and add 2. A 40-year-old human matches a cat of 6 years.
- Is one cat year equal to seven human years?No. Times seven makes a 1-year-old cat a 7-year-old child, although it is fully grown, and a 20-year-old cat a 140-year-old. The rule used here gives 15 and 96.
Sources
- J. Quimby and others: 2021 AAHA/AAFP Feline Life Stage Guidelines (Journal of Feline Medicine and Surgery, 2021) – the four life stages: kitten, young adult, mature adult and senior
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