Dog Age Calculator — Dog Years to Human Years

Convert your dog’s age to human years by size using the AVMA 15-9-5 guideline, and compare it with the 2020 DNA-methylation formula.

Dogs grow up fast and then age more slowly, so the old rule of seven human years per dog year does not fit. This calculator uses the American Veterinary Medical Association guideline: about 15 human years for the first year, 9 more for the second, then a few years for each year after, with larger dogs ageing faster. It also shows the 2020 DNA-methylation formula for comparison.

How to use this tool

Enter your dog’s age in years and months.
Choose the size your dog is, or will be, as an adult.
Read the human-age estimate and compare the other methods.
Use the chart to see how the gap grows with age for each size.

Formula

Human age = 15 (year 1) + 9 (year 2) + k × (dog age − 2)

k is about 4 for small dogs, 5 for medium (the AVMA figure), 6 for large and 7 for giant breeds; the size steps are a common extension and sources differ slightly. Ages inside a year are scaled in proportion. The DNA-methylation formula from a 2020 Cell Systems study is 16 × ln(dog age) + 31, where ln is the natural logarithm.

Example

A 5-year-old medium dog is about 15 + 9 + 3 × 5 = 39 in human years. A small dog the same age is about 36, and a giant breed about 45. The DNA-methylation formula gives 16 × ln(5) + 31 = 56.8, and the old seven-year rule gives 35.

Frequently asked questions

Is one dog year really seven human years?

No. Dogs reach adulthood within their first year or two, so early years count for much more than seven, and later years count for less in small dogs.

Why do big dogs age faster?

Large and giant breeds tend to have shorter lifespans, so they reach old age sooner. The AKC notes that small dogs are often considered seniors at around 7, and large breeds at around 5 to 6.

Which method is most accurate?

Neither is exact. The 15-9-5 guideline is the one the AVMA and AKC publish for medium dogs. The DNA formula was built from about 100 Labrador retrievers, so it may not suit other breeds.

Sources

This tool gives an estimate for general information only. It is not financial, tax, legal or medical advice — check with a qualified professional before you rely on the result.

Last updated: 2026-10-30