Dog & Cat Age in Human Years
Convert your dog's or cat's age into human years — by size for dogs — using veterinary guidelines and the 2020 DNA-methylation formula.
For general information only — not medical advice. Results are estimates; talk to a doctor or qualified health professional about your own health.
How to use
- 1Choose dog or cat and enter the age in years (decimals allowed).
- 2For dogs, pick the adult size.
How it's calculated
Common vet guide: first year = 15 human years, second = +9 (24), then +4 per year for cats and small dogs, +5 medium, +6 large, +7 giant. The epigenetic clock (Wang et al., 2020): human age = 16 × ln(dog age) + 31.
Frequently asked questions
Is one dog year really seven human years?
No — dogs age much faster in the first two years, then more slowly. Larger breeds age faster later in life.
Why does size matter?
Large and giant breeds have shorter lifespans and are considered senior earlier (around 6–7) than small breeds (around 10–12).
Which formula is right?
Both are approximations. The DNA formula fits Labrador data; the size-based guide is what many vets use.