Reference chart
Cat Years to Human Years Chart
By &Pixels, the studio that builds MyCalculator.to. Life stages follow AAFP and AAHA feline guidance, named at the foot of this page.
One column, not four. Cats age on the same curve whatever their size, which is the first thing that surprises anyone arriving from a dog chart.
How old is a cat in human years?
A cat’s first year is worth about fifteen human years and its second about nine more, putting a two-year-old cat at roughly twenty-four. Every year after that adds about four. A ten-year-old cat is around fifty-six, and a twenty-year-old is around ninety-six.
Unlike dogs, size does not enter into it. A large breed cat and a small one follow the same curve, so this chart needs one column where the dog equivalent needs four. What does change a cat’s expected lifespan, and change it considerably, is whether it goes outside.
Cat age in human years
| Cat’s age | Human equivalent | Life stage |
|---|---|---|
| 1 month | 1 year | Kitten |
| 3 months | 4 years | Kitten |
| 6 months | 10 years | Kitten |
| 1 year | 15 years | Young adult |
| 2 years | 24 years | Young adult |
| 3 years | 28 years | Young adult |
| 4 years | 32 years | Young adult |
| 5 years | 36 years | Mature adult |
| 6 years | 40 years | Mature adult |
| 7 years | 44 years | Mature adult |
| 8 years | 48 years | Mature adult |
| 9 years | 52 years | Mature adult |
| 10 years | 56 years | Senior |
| 11 years | 60 years | Senior |
| 12 years | 64 years | Senior |
| 13 years | 68 years | Senior |
| 14 years | 72 years | Senior |
| 15 years | 76 years | Senior |
| 16 years | 80 years | Senior |
| 18 years | 88 years | Senior |
| 20 years | 96 years | Senior |
The top of the table is the part worth reading slowly. A six-month-old kitten is already around ten in human terms, which is why cats can reproduce long before anyone thinks of them as grown.
The calculators behind this
How to read a cat’s age
- Count the first year as fifteen. A one-year-old cat is roughly a fifteen-year-old human: fully grown, not fully done.
- Add nine for the second year. That puts a two-year-old at about twenty-four. Most of a cat’s ageing is finished by here.
- Add four for every year after. Steady and linear from there, which is why the cat chart has one column where the dog chart needs four.
- Ignore the breed. Size and breed change a dog’s ageing considerably and a cat’s barely at all.
- Adjust for indoor or outdoor instead. That is the variable that actually moves feline lifespan, and it moves it a long way.
Ten years is the number to keep. That is where a cat becomes senior, and where twice-yearly checks and kidney values start being recommended, because the conditions that shorten feline lives arrive quietly and are far more treatable when found early.
For one age rather than the whole table, the cat age calculator gives the figure and the life stage. If you have a dog as well, the dog years chart is a different shape entirely, because there size changes everything.
Formula & Methodology
Did you know? A cat's first two years cover roughly the same ground as a dog's, but the curves separate completely afterwards. By fifteen, a cat is around seventy-six in human terms while a giant breed dog would be past a hundred and fifteen.
Sources
- American Association of Feline Practitioners and American Animal Hospital Association, Feline Life Stage Guidelines
- International Cat Care, life stage classification
- American Veterinary Medical Association, senior pet care guidance