How to calculate your dog's age in human years
- Enter your dog's age in years and months.
- Choose its size by adult weight: small, medium, large or giant.
- See the human-age equivalent, life stage, a DNA-clock estimate and an age table for that size.
Dog years explained
Dogs mature fast: a one-year-old dog is roughly like a 15-year-old human, and a two-year-old like a 24-year-old. After that, each year adds about 4 human years for small dogs, 5 for medium dogs, 6 for large dogs and 7 for giant breeds. Big dogs age faster and have shorter life expectancies: a Chihuahua may live 15–17 years, a Great Dane 8–10. So a 10-year-old Jack Russell is about 56 in human years, while a 10-year-old Great Dane is closer to 80.
The DNA-clock formula from a 2020 study of Labradors (16 × ln(age) + 31) suggests the first years count even more: a two-year-old dog is roughly like a 42-year-old in molecular terms. Senior dogs benefit from twice-yearly vet visits, joint care and an adjusted diet. The calculator runs in your browser.
FAQ
Is one dog year really seven human years?
No. Dogs age much faster at first and then more slowly; size also matters.
How old is a 3-year-old dog in human years?
About 28–31, depending on size.
At what age is a dog a senior?
Around 7 for small and medium breeds, 5–6 for large and giant breeds.