Dog age calculator in human years
The one-year-equals-seven rule is not accurate: dogs age fast in the first two years, then the pace depends on size.
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How to use it
- Enter dog age and dog weight.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Read directly from the AAHA chart (2019), adapted from the Dog Owner's Home Veterinary Handbook, Appendix B: year 1 = 15, year 2 = 24, then 4 to 9 years per year by weight. Epigenetic clock (Wang et al. 2020) = 16 × ln(dog age) + 31.
Example
Inputs: Dog age = 7 years, Dog weight = Medium: 9.5 to 22.7 kg (21 to 50 lb). Result: Age in human years (AAHA chart): 47 years; Epigenetic clock estimate (Wang 2020): 62.1 years.
Limits and caveats
- The chart is a general guide by weight; breed and health change real ageing.
- Whole years only, because the chart gives no values between years.
- The epigenetic estimate comes from a study of Labrador retrievers, so treat it as a comparison.
Questions about this tool
Is one dog year seven human years?
No. By the chart the first year is about 15 human years and the second 24, then each year adds 4 to 9 years depending on size.
Why do big dogs age faster?
Large and giant dogs live shorter lives on average, so their equivalent age climbs faster after year three.
Where do the numbers come from?
The age chart published by the American Animal Hospital Association (AAHA) in 2019, adapted from the Dog Owner's Home Veterinary Handbook.