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Dog age calculator: dog years to human years
Enter an age and your dog’s size. You get the age on the other side by the veterinary charts, the DNA clock of a 2020 study for comparison, and the AAHA life stage.
28human yearsfor a 3-year-old medium dog (21 to 50 lb)
- life stage: Young adult
- senior from 10 years
- DNA clock: 48.6 human years
- 7× rule: 21 human years
This age is outside the 6 months to 20 years the charts cover, so the figure carries the chart’s last line on: read it as a rough guide.
The DNA clock was fitted on dogs up to 16 years old, so its figure here is past its own data.
How many dog years is one human year? Not seven. A dog’s first year is about 15 human years and its second about 9 more (AVMA and the Merck Veterinary Manual agree on 15 at 1 and 24 at 2). After that each year adds about 4 human years for a small dog, 4 to 5 for a medium one, 5 to 6 for a large one and 7 to 8 for a giant one (PetMD). The calculator uses the AVMA chart for a medium dog and the middle of each range for the other sizes.
The sources disagree, and the page shows it. The DNA clock of Wang et al. (2020), fitted on Labrador retrievers only, makes a young dog much older: 31 human years at 1, against 15 on the charts. The AAHA guidelines do not convert ages at all; they place a dog in a life stage, which is the line this page gives under the figure.
Ages are estimates. AVMA notes that many factors, weight and breed among them, change how a dog ages: ask your veterinarian where your dog is.
The human age follows the AVMA chart for a medium dog and, for the other sizes, 15 at 1 and 24 at 2 (Merck) then 4, 5.5 or 7.5 human years a year (the middle of PetMD’s ranges). The DNA clock is 16 × ln(dog age) + 31 (Wang et al., 2020). How we work it out.