About the Cat Years Calculator
Cats grow up fast. A one-year-old cat is roughly equivalent to a 15-year-old human, and by two it has reached about 24 human years. After that, each cat year adds around four human years. This calculator applies that formula, which is endorsed by the International Cat Care organisation and the American Association of Feline Practitioners, and maps the result onto the six feline life stages used by veterinarians.
Unlike dogs, cat ageing does not vary much with breed size, but lifestyle matters: indoor cats commonly live 13 to 17 years, and many reach 20, while cats with outdoor access face traffic, disease and fights that shorten average lifespan.
Use the life stage to time care: kitten vaccinations and neutering, weight management in the prime years, and senior screening for kidney disease, hyperthyroidism and arthritis from around 11 years.
How to use the Cat Years Calculator
- Enter your cat's age in years, using decimals for kittens.
- Choose whether your cat lives indoors or has outdoor access.
- Read the human-equivalent age, life stage and typical lifespan.