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Why not "multiply by 7"?
A 2020 study in Cell Systems (Wang et al.) compared DNA methylation in Labrador retrievers and humans and proposed human age ≈ 16 × ln(dog age) + 31. Dogs age fast early: a 1-year-old dog is about 31 in human terms; a 4-year-old about 53. The study used one breed, so treat results as an estimate.
| Dog age | Human years (≈) |
|---|---|
| 1 | 31.0 |
| 2 | 42.1 |
| 3 | 48.6 |
| 4 | 53.2 |
| 5 | 56.8 |
| 6 | 59.7 |
| 8 | 64.3 |
| 10 | 67.8 |
| 12 | 70.8 |
| 14 | 73.2 |
| 16 | 75.4 |
Worked example
With the formula 16 × ln(age) + 31, a 7-year-old dog is about 62 in human years (16 × 1.946 + 31). Compare that with the old "× 7" rule, which says 49. The formula is steep early and flattens later, which matches how dogs mature quickly in their first two years.
Size still matters
The study behind the formula used Labrador retrievers. Large and giant breeds tend to age faster and live shorter lives than small breeds, which is why the American Veterinary Medical Association's rough guide (15 human years for year one, about 9 for year two, then about 4 to 5 a year) gives a range rather than one number.
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Frequently asked questions
Is 1 dog year 7 human years?
No. The 7× rule is a myth; dogs mature much faster in their first year.
Is a dog year really seven human years?
No. A 1-year-old dog is closer to 31 in human terms by the methylation formula, and the gap narrows with age.
Does the formula work for puppies under one year?
It gives a rough figure, but puppies change week to week; your vet's assessment is better at that age.