Dog Age Calculator
Convert your dog's age to human years based on size, using the veterinary chart and the newer epigenetic formula.
Forget "one dog year equals seven"
Dogs mature very quickly in their first two years, then age more steadily, and large breeds age faster than small ones. The veterinary rule of thumb is roughly:
- The first year equals about 15 human years.
- The second year adds about 9 more (24 at age two).
- After that, each year adds about 4 to 7 human years depending on size.
A 7-year-old medium dog is about 47 in human years; a giant breed of the same age is about 56.
The epigenetic formula
A 2020 study from the University of California San Diego compared DNA methylation in Labrador retrievers and humans and proposed: human age = 16 × ln(dog age) + 31. It makes a 1-year-old dog about 31 and a 7-year-old about 62. It was based on one breed, so the size-based chart is still the more common guide.
When is a dog a senior?
Giant breeds can be considered senior from about 5–6 years, large breeds from 7–8 and small breeds from around 10. Senior dogs benefit from twice-yearly vet checkups.
Frequently asked questions
How old is a 10-year-old dog in human years?
About 56 for a small dog, 60 for a medium dog, 66 for a large dog and 79 for a giant breed.
Why do small dogs live longer?
Large breeds grow and age faster, and are prone to age-related conditions earlier. The exact reasons are still being researched.
Is the 7-year rule wrong?
It is a rough average. It underestimates the first years and overestimates later years for small dogs.
Last reviewed October 2026. Results are estimates; check important decisions with a qualified professional.