Everyday Life
Dog Years
Updated 2025-08-31
Definition
The old rule that one dog year equals seven human years is a myth. Modern veterinary research, including a 2019 epigenetic clock study from UC San Diego, shows dogs age much faster in their first two years: a one-year-old dog is developmentally about 15 in human equivalent, and a two-year-old about 24. After that, aging slows and depends on size. Small dogs (under 20 lbs) add roughly 4 human years per dog year; medium dogs add 5; large dogs (50+ lbs) add 6; giant breeds like Great Danes add 7-9 per year and typically live only 7-10 years total.
Primary source: AVMA dog age guide
Related Calculators
- Dog Age Calculator - Convert your dog's age to human years using the latest veterinary science (not the outdated 7× rule).
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