Calculate your dog's age in human years using size-specific formulas. Free online dog age calculator for small, medium, and large breeds.
The dog age calculator converts your dog's age to human-equivalent years using modern, size-specific formulas. Unlike the old "multiply by 7" rule, this calculator accounts for the fact that dogs age faster in their first two years and that aging rates differ significantly between small, medium, and large breeds.
Year 1 = 15 human years
Year 2 = +9 human years (total: 24)
Each subsequent year: Small +4, Medium +5, Large +6The first year of a dog's life is roughly equivalent to 15 human years due to rapid development. The second year adds 9 years (totaling 24). After that, small breeds age slower (+4/year), medium breeds at a moderate rate (+5/year), and large breeds age faster (+6/year). This reflects that larger dogs have shorter lifespans.
| Input | Output |
|---|---|
| 5-year-old small dog | 36 human years (Adult) |
| 3-year-old large dog | 30 human years (Young Adult) |
| 10-year-old medium dog | 64 human years (Mature) |