Common questions
Is the “multiply by 7” rule accurate?
No. The American Veterinary Medical Association says dogs do not age at a rate of seven human years for each year. A common AVMA guideline for a medium-sized dog is about 15 human years in the first year, about nine more in the second year, and about five human years for each year after that. This calculator uses the size-specific figures on the AAHA physiological-age poster, which also shows that larger dogs age faster after year two.
Why does dog size change the result?
Larger dogs usually have shorter lives than smaller dogs, so the published chart gives a higher human-year equivalent for a large or giant dog than for a small dog of the same age. The weight groups here (20 lb or less, 21–50 lb, 51–90 lb, and over 90 lb) match the AAHA poster. Breed, body condition, and health also matter, so the number is only an estimate.
Is this age an exact number?
No. Whole-year results are taken from the published chart. Ages that fall between listed years are a straight-line estimate, and the result says so. We do not invent a number past the last published year for that size. The 2019 AAHA Canine Life Stage Guidelines also note that, for clinical care, life stages are more useful than converting a dog's age into human years. Ask your veterinarian about your own pet.
Sources
Whole-year numbers on this page are taken from the charts below. Ages that fall between listed years are a straight-line estimate, and we say so in the result. We do not invent a number past the last published year for that size.
- AAHA, My Pet’s Physiological Age (2019 poster). Dog figures by size (20 lb or less, 21–50 lb, 51–90 lb, over 90 lb) are adapted on that poster from Dog Owner’s Home Veterinary Handbook, Appendix B. Cat figures on the same poster are adapted from the AAFP–AAHA Feline Life Stage Guidelines.
- AVMA, Pets age faster than people (a similar year-by-year chart for cats and for a medium dog, 21–50 lb; the AVMA notes these are approximate and that weight and breed can change how a pet ages)
- American Kennel Club, How old is my dog in human years? (quotes the AVMA’s medium-dog guideline: about 15 human years in year one, about 9 more in year two, then about 5 per year after that, and states that dogs do not age at a flat rate of 7 human years per year)
- 2019 AAHA Canine Life Stage Guidelines (for clinical care, AAHA prefers life stages — puppy, young adult, mature adult, senior — over converting a dog’s age into human years)
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