Dog Age Calculator
Convert your dog's age into human years using the vet-based method that adjusts for breed size — because small dogs and giant breeds age at very different rates.
The old "multiply by seven" rule is a myth. Dogs mature very quickly in their first two years and then age at a pace that depends heavily on their size — small breeds live longest and age slowest, while giant breeds age fastest and are considered senior years earlier. This calculator uses the American Veterinary Medical Association and American Kennel Club guideline, which counts the first year as 15 human years, the second as 9 more, and each year after that as 4 to 7 human years depending on your dog's size.
How dog years convert to human years
The first two years are the same for all sizes; after that, bigger dogs gain more human years per calendar year.
Year 2 = +9 (24 total at age 2)
Each year after = +4 small · +5 medium · +6 large · +7 giant
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 |
| 5 years | 36 | 39 | 42 | 45 |
| 10 years | 56 | 64 | 72 | 80 |
| 15 years | 76 | 89 | 102 | 115 |
Worked example
A 5-year-old medium-sized dog (20–50 lb):
| Years 1–2 | 24 |
| 3 more years × 5 | 15 |
| Human-age equivalent | ≈ 39 years |
Why size changes everything
Larger dogs have shorter lifespans and reach old age sooner, so each of their later years counts for more human years. Small and toy breeds often live into their mid-teens and are considered senior around seven, while giant breeds may be senior by five or six. Breed, weight, diet and veterinary care all shift the picture, so treat the result as a good estimate rather than an exact figure — and keep up regular check-ups as your dog enters its senior years.