How dog years are calculated
The calculator uses the widely used veterinary chart that groups dogs by adult weight, interpolating between whole years. It also shows the epigenetic (DNA-based) formula for comparison.
DNA-based estimate: Human age = 16 × ln(Dog age) + 31
Example: A 5-year-old medium dog (21–50 lb) is about 36 in human years — a mature adult. The old ×7 rule would say 35; the DNA formula gives 57, because it assumes dogs age especially fast in early adulthood.
Dog life stages
- Puppy: birth to about 1 year (up to 2 for giant breeds).
- Young adult and mature adult: the long middle years.
- Senior: from about 10 years in small dogs, 8 in medium, 7 in large and 6 in giant breeds. Twice-yearly vet checks are recommended.
Adjust food as your dog ages with the dog food calculator.
Frequently asked questions
Is one dog year really seven human years?
No. Dogs mature very quickly: 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 4–7 human years depending on size.
Why do large dogs age faster?
Large and giant breeds have shorter life spans and reach senior age sooner — often around 6–7 years, compared with 10 or more for small breeds.
What is the DNA-based formula?
A 2020 study of DNA methylation in Labrador retrievers (Wang et al., Cell Systems) proposed human age = 16 × ln(dog age) + 31. It fits the fast early aging but was built on one breed.
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.