Convert a dog's age to human years with the 2020 epigenetic formula and a size-based rule of thumb. Runs on your device.
A dog's age in human years can be estimated from a formula fitted to biological data, or from a simple rule of thumb. The formula is human age = 16 × ln(dog age) + 31, where ln is the natural logarithm. It comes from Wang and colleagues in Cell Systems in 2020, who compared DNA methylation changes in Labrador retrievers with those in people. For a 7-year-old dog, 16 × ln(7) + 31 = 16 × 1.9459 + 31 = 62.13, shown as 62. The second method is a rule of thumb: 15 human years for year one, 24 at the end of year two, then 4 more per dog year for small and medium dogs or 5 for large and giant dogs. A 7-year-old medium dog is 24 + 4 × 5 = 44.
The formula rises fast in the first years and then slowly, because it uses a logarithm: a 1-year-old comes out at 31, a 2-year-old at 42, a 10-year-old at 68 and a 15-year-old at 74. The rule of thumb is a straight line after year two, so a medium dog is 56 at 10 years and 76 at 15 years, and a large dog is 64 and 89. They can disagree by 10 or 20 years, and neither is a measured age. The table at the bottom lists both for common ages so you can see where they diverge. The formula does not use your dog's size; only the rule of thumb does.
The epigenetic formula is meant for dogs of about 1 year and older. At 1 year it gives 31, and for a younger dog the logarithm falls toward zero and then below it, which is not a sensible age. So under 12 months the page shows only the rule of thumb, which takes 15 years for a full first year and scales it down: 6 months is 7.5, shown as 8. A notice says why the formula is missing. Ages up to 30 years are accepted. Months go from 0 to 11, and you can leave years or months empty.
Neither method is exact. The formula was fitted on Labrador retrievers, a single breed, and breeds differ in how long they live and how fast they age. The rule of thumb is a convenience, not a result from a study, and its size bands are rough. Health, diet and care matter more than any conversion, and the page gives no medical or veterinary advice. For questions about your dog's life stage, vaccinations or senior care, ask a vet, who can judge your dog rather than an average.
Use human age = 16 × ln(dog age) + 31 for dogs over about 1 year. A 7-year-old dog is 16 × ln(7) + 31 = 62.13, so about 62. A simple alternative for a medium dog is 24 + 4 × (age − 2), which gives 44.
It comes from Wang et al., Cell Systems, 2020, which compared DNA methylation changes with age in Labrador retrievers and in humans. It is a fitted curve for that breed, not a law, so treat the answer as a rough guide for any dog.
It is a flat multiplier, and dogs do not age at a flat rate: a 1-year-old dog is far past 7 in human terms. This page shows the epigenetic formula, where 1 year is 31 and 2 years is 42, beside a size-based rule where year one is 15 and year two is 24.
By the epigenetic formula, 16 × ln(10) + 31 = 67.84, about 68. By the rule of thumb it is 24 + 4 × 8 = 56 for a small or medium dog and 24 + 5 × 8 = 64 for a large or giant one.
Only the rule of thumb is shown. At 6 months it gives 15 × 0.5 = 7.5, shown as 8. The epigenetic formula is not used under 1 year, because 16 × ln(0.5) + 31 = 19.9 is not a reliable figure for such a young dog.
No. The numbers stay in this tab and are not stored on your device or sent anywhere. Reloading the page puts the example back. The page only counts that a result was shown, without any of your numbers.