How to calculate your pet's age in human years
- Choose dog or cat.
- Enter your pet's age in years and months.
- For dogs, choose the size by adult weight, because large breeds age faster.
- Read the human-age equivalent, the life stage and a reference table, and share the result.
Why "multiply by 7" is wrong
The popular rule that one dog or cat year equals seven human years is a myth. Pets mature very quickly at first: by their first birthday most dogs and cats are physically similar to a 15-year-old teenager, and by two they are roughly like a 24-year-old adult. After that, ageing slows down. Veterinary charts, such as those used by the American Animal Hospital Association and the American Veterinary Medical Association, add about 4 human years per year for cats and small dogs, 5 for medium dogs, 6 for large dogs and 7 for giant breeds, because big dogs have shorter life spans.
For dogs, the page also shows a newer formula from a 2020 study by Wang and colleagues that compared DNA methylation (an "epigenetic clock") in Labrador retrievers and humans: human age = 16 × ln(dog age) + 31. It suggests dogs age especially fast in the first years. Both methods are estimates, and diet, genetics and care make a big difference. Regular vet check-ups become more important from the senior stage. The calculation runs in your browser.
How old is a 10-year-old dog in human years?
About 56 for a small dog, 64 for a medium dog and 72 for a large dog.
How old is a 15-year-old cat in human years?
About 76.
When is a dog considered senior?
Often from about 7 years, or 5–6 years for large and giant breeds.