Dog's age
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How this calculator works
The old rule of multiplying by seven is wrong because dogs mature much faster early in life. The American Veterinary Medical Association's guideline is that a medium-sized dog's first year equals about 15 human years, the second adds about 9, and each year after adds about 5. A 2020 study of Labrador retrievers derived a formula from DNA changes with age, shown alongside for comparison.
Formula
- Guideline: 15 human years at age 1, 24 at age 2, then +5 per year
- Between 0 and 2 years the guideline is interpolated
- DNA-based (Wang et al. 2020): human age = 16 × ln(dog age) + 31, for dogs 1 year and older
Worked example
A 5-year-old dog
- Dog's age
- 5 years
ResultAbout 39 human years
A 5-year-old medium-sized dog by the veterinary guideline.
Things to keep in mind
- Small breeds age more slowly in later life and giant breeds faster, so treat the result as a general guide.
Frequently asked questions
Is one dog year really seven human years?
No. Dogs reach adulthood within about two years, then age more slowly. A 1-year-old dog is closer to a 15-year-old person than to a 7-year-old.
Do small dogs live longer than large dogs?
Generally yes. Small breeds are often considered senior at around 10 to 12 years, while giant breeds may be senior at 6 or 7.
Why do the two methods disagree?
The guideline is a rule of thumb for medium dogs. The DNA-based formula comes from one breed and rises steeply in the first years and flattens later.
Sources
More in Everyday Life
Results are estimates based on the values you enter and the published method shown above. They do not replace professional medical, financial or legal advice. Method reviewed October 7, 2026. About this site