Dog years to human years
A dog's first year counts as about 15 human years, the second adds 9 more, and every year after that is roughly 5. So a 3-year-old dog is about 29, not 21 — the “times seven” rule is a myth.
0–30 years
A rule-of-thumb estimate, not veterinary advice. Breed and size affect real longevity — a bigger breed ages faster than a small one.
Dog years chart
Both methods side by side. The two disagree most for young dogs.
| Dog age | Vet guideline | DNA formula |
|---|---|---|
| 1 year | 15 | 31 |
| 2 years | 24 | 42 |
| 3 years | 29 | 49 |
| 4 years | 34 | 53 |
| 5 years | 39 | 57 |
| 6 years | 44 | 60 |
| 7 years | 49 | 62 |
| 8 years | 54 | 64 |
| 9 years | 59 | 66 |
| 10 years | 64 | 68 |
| 11 years | 69 | 69 |
| 12 years | 74 | 71 |
| 13 years | 79 | 72 |
| 14 years | 84 | 73 |
| 15 years | 89 | 74 |
| 16 years | 94 | 75 |
Where these numbers come from
The vet guideline is the rule of thumb the American Veterinary Medical Association describes: about 15 human years for a medium dog's first year, about 9 for the second, and roughly 5 for each year after.
The DNA formula comes from a 2020 UC San Diego study (Wang et al., Cell Systems) that tracked age-related chemical marks on the DNA of 104 Labrador Retrievers and matched them to human data: human age = 16 × ln(dog age) + 31. It was fitted on one breed, so treat it as a second opinion rather than the answer.
Size matters either way: giant breeds age faster and live shorter lives than small ones.
Have a cat too?