🎂 Dog Age Calculator: Dog Years to Human Years
“Multiply by seven” is a myth. Dogs grow up fast in their first two years, and big dogs age faster than small ones after that. Enter your dog’s age and size.
Why size matters
A one-year-old dog is roughly a 15-year-old person, and a two-year-old about 24, whatever its size. After that, small dogs add around four human years a year, while large dogs add six or more — which is why giant breeds are seniors by about seven.
The DNA formula
A 2020 study compared chemical changes in DNA as dogs and people age and proposed human age = 16 × ln(dog age) + 31. It makes a one-year-old dog about 31 in human terms, then slows sharply. It was based on Labrador Retrievers, so the size chart remains the practical guide.
Frequently asked questions
How old is a 7-year-old dog in human years?
About 44 for a small dog, 47 for a medium dog and 50 for a large dog on the size-based chart.
Is one dog year really seven human years?
No. Dogs mature much faster early on — a one-year-old is about 15 in human years — and the rate after that depends on size.
When is a dog a senior?
Roughly in the last quarter of its expected lifespan — around 7–8 for large breeds and 10–11 for small ones.
Sources
These calculators give general estimates for healthy pets. They are not veterinary advice — if your pet is unwell or has eaten something it shouldn’t, call your vet.