How cat age is calculated
Cats grow up fast. International Cat Care's chart puts a 1-year-old cat at 15 human years and a 2-year-old at 24. After that, each extra cat year adds 4 human years.
Between 1 and 2 the calculator adds 9 human years per cat year, so 18 months comes out at 19.5. It starts at 1 year because kittens age much faster in their first months than any straight line can show.
Worked example
A 4-year-old cat is 24 + (4 − 2) × 4 = 32 in human years. The seven-times rule would say 28.
As a guide, the chart gives 15 human years at age 1, 24 at 2, 56 at 10, 76 at 15 and 96 at 20.
Why not multiply by seven?
Multiplying by seven assumes cats age at the same pace all their lives. It makes young cats seem far too young: by their first birthday most cats are close to adult size, which fits 15 human years better than 7.
It also makes older cats seem older than they are. A 15-year-old cat is about 76 by the chart, but 105 by the seven-times rule.
Every cat ages differently, so the result is a guide rather than a measure of your cat's health. Talk to your vet about your cat's needs as it gets older.
Inputs for the cat years calculator
Your cat's age
Enter your cat's age in years. Use decimals for part years, for example 1.5 for 18 months. The calculator covers ages from 1 to 30.
CALCULATOR QUESTIONS
Cat years calculator questions
How old is my cat in human years?
Enter its age above. As a guide, a 1-year-old cat is about 15 in human years, a 2-year-old about 24, and each year after that adds about 4.
Is one cat year equal to seven human years?
No. Cats age much faster in their first two years and more slowly after that, so the seven-times rule is a poor fit at both ends of life.
When is a cat considered senior?
Older cats need extra care as their health changes. Ask your vet when to start senior health checks for your cat.
How do I enter a kitten's age?
The calculator starts at 1 year, when a cat is about 15 in human years. Kittens grow up very quickly in their first year, so check International Cat Care's chart for the month-by-month equivalents.