How old is my dog in human years?
A 7-year-old medium-size dog is about 47 in human years on the AVMA chart, and about 62 by the 2020 DNA-clock formula. Enter your dog’s age and size to see both numbers and its life stage.
Two ways to count dog years
They answer slightly different questions, so they don’t match at every age.
The AVMA chart
The American Veterinary Medical Association’s “Pets age faster than people” chart counts a dog’s first year as 15 human years and its second as 9 more, so a 2-year-old is 24. After that it adds 4 to 6 years per year, reaching 87 at 16. The chart is for a medium-size dog of 21 to 50 lb, and AVMA notes that weight and breed may affect how a dog ages.
Year 1 = 15, year 2 = 24, then about 4 to 6 a yearBetween whole years, this site fills in the months on a straight line.
The DNA-clock formula
In 2020, researchers at UC San Diego compared age-related chemical marks on DNA (methylation) in 104 dogs, mostly Labrador retrievers, with the same marks in 320 people. The matches fit a curve that climbs fast in puppyhood and flattens in old age.
Human age = 16 × ln(dog age) + 31ln is the natural logarithm. For a 7-year-old: 16 × 1.946 + 31 = 62.1.
The study covered dogs from a few weeks to 16 years old, and its authors say breeds with longer or shorter lives could follow a different curve. AVMA calls its own chart ages approximate. Neither replaces your vet’s look at your own dog.
Why “multiply by 7” is wrong
The AVMA says plainly that dogs don’t age 7 human years for every dog year.
- Puppies grow up fastTimes 7 makes a 1-year-old dog a 7-year-old child. The AVMA chart says 15, and the DNA-clock formula says 31. The 2020 study lines up a dog’s adolescence, 6 months to 2 years, with roughly 12 to 25 in people.
- Aging slows down laterAfter age 2 the AVMA chart adds 4 to 6 years per dog year, not 7, and the DNA clock adds less and less each year.
- Where 7 came fromUC Davis’s veterinary school says the rule likely came from average lifespans of about 70 years for people and 10 for dogs. That average hides how uneven a dog’s aging is.
What your dog’s size changes
Bigger breeds tend to have shorter lives, so they reach their senior years sooner.
| Size and adult weight | Senior from about |
|---|---|
| Small or toyless than 20 lb | 8 to 11 years |
| Medium20 to 50 lb | 8 to 10 years |
| Large50 to 90 lb | 8 to 9 years |
| Giantmore than 90 lb | 6 to 7 years |
AVMA counts a dog as senior in the last 25 percent of its breed’s expected lifespan; the ages above are its averages for each size group. AVMA does not publish a year-by-year human-age number for small, large or giant dogs, so this site doesn’t make one up. The human age on the card always comes from the medium-dog chart or the formula, and your dog’s size moves its life stage. The size charts on many pet sites don’t name a veterinary source. See the dog years chart for every age from 1 to 20.
Dog life stages
From the American Animal Hospital Association’s 2019 canine life stage guidelines.
| Stage | When |
|---|---|
| Puppy | Birth until rapid growth stops, about 6 to 9 months depending on breed and size |
| Young adult | Until the dog is physically and socially mature, by 3 to 4 years in most dogs |
| Mature adult | From maturity until the last 25% of the expected lifespan |
| Senior | The last 25% of the expected lifespan, which depends on breed and size |
| End of life | A final stage that depends on illness, not age |
Questions people ask
- How old is a 1-year-old dog in human years?
- About 15 on the AVMA chart for a medium-size dog. The 2020 DNA-clock formula gives 31, because its curve rises steeply in the first year.
- Is one dog year really seven human years?
- No. The AVMA says dogs don’t age at 7 human years per year. Dogs age fastest in their first two years and more slowly after that.
- Why does the DNA formula give a different number than the vet chart?
- The chart is AVMA’s approximate guide for medium dogs. The formula comes from matching DNA methylation in Labrador retrievers with people, and its curve is steeper early and flatter late. Up to 12 years the formula reads higher; from 13 it reads lower.
- Do small dogs age slower than big dogs?
- In their later years, generally yes. AVMA says larger breeds tend to have shorter lifespans, and it puts the start of the senior years at 8 to 11 for small dogs but 6 to 7 for giant breeds.
- When is my dog a senior?
- In the last 25% of its expected lifespan. On average that is 8 to 11 years for small dogs, 8 to 10 for medium, 8 to 9 for large and 6 to 7 for giant breeds, according to AVMA.
- Is this veterinary advice?
- No. These are estimates from published charts and research. Your vet can tell you how your own dog is aging.
Sources
Every number on this page comes from these, checked October 2, 2026. Human-age equivalents are estimates, not veterinary advice.
- AVMA, “Pets age faster than people” (PDF). Dog column for a medium-size dog of 21 to 50 lb, ages 1 to 16; cat column, ages 1 to 16. AVMA adds that pet ages are approximate and that weight and breed may influence aging.
- AVMA, “Caring for senior cats and dogs.” Dog size groups by weight, the age each group becomes senior, cats senior after about 10, and the statement that dogs don’t age 7 human years per year.
- AVMA “Senior Pets” client brochure, revision 7/10, since replaced by a 2023 edition without the chart (archived copy). Human-age ranges from small to very large dogs at 7, 10, 15 and 20 years.
- Wang T, Ma J, Hogan AN, et al. “Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome.” Cell Systems 11 (2020). The formula human age = 16 ln(dog age) + 31, from 104 dogs, mostly Labrador retrievers, aged a few weeks to 16 years. See also the UC San Diego news release.
- UC Davis School of Veterinary Medicine, “Calculating your dog’s age.” Why the times-7 rule is inaccurate and where it likely came from.
- 2019 AAHA Canine Life Stage Guidelines (PDF). Puppy, young adult, mature adult, senior and end-of-life stages.