Dog Age in Human Years Calculator
Convert your dog's age to human years using the AVMA 2025 formula, calibrated by breed size.
Calculations use the AVMA's 2025 size-adjusted formula. The familiar “1 dog year = 7 human years” rule is a discredited approximation — actual aging is non-linear and varies materially by breed size.
Frequently asked questions
Is the “1 dog year = 7 human years” rule accurate?
No. That rule is a discredited approximation. Modern research shows dogs age much faster in their first two years (a 1-year-old dog is roughly 15 in human years) and slower thereafter — with the rate of aging varying significantly by breed size. Larger breeds age faster than smaller ones.
Why do larger dogs age faster?
Larger breeds have shorter average lifespans. A Great Dane's median lifespan is 7-10 years; a Chihuahua's is 12-20. The exact cause isn't fully understood, but it's linked to faster cell turnover and earlier onset of age-related diseases in large breeds.
When is my dog considered a senior?
Small breeds: around 11 years. Medium: around 9. Large: around 8. Giant breeds: around 7. Regular vet checkups become more important in the senior stage to catch joint, dental, and organ issues early.