The math
How many dog years are there, really?
The old "multiply by seven" rule is a myth. Dogs mature into adolescence within about two years, then age at a rate tied to their adult size — bigger dogs pack more aging into fewer calendar years. Use the calculator below to convert any dog's age.
equivalent to
28.5
human years
Medium breeds sit close to the historic "1 year = 7 years" myth, though the real curve is steeper early on.
Year one is a sprint
Most dogs reach sexual maturity and near-adult size within 12 months — a pace of development that would take a human roughly 15 years.
Size changes the slope
After adolescence, small breeds age the slowest per calendar year, while giant breeds age fastest — part of why smaller dogs tend to live longer.
Age at a glance
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 yrs | 15 | 15 | 15 | 15 |
| 2 yrs | 24 | 24 | 24 | 24 |
| 5 yrs | 36 | 37.5 | 39.8 | 43.2 |
| 8 yrs | 48 | 51 | 55.5 | 62.4 |
| 12 yrs | 64 | 69 | 76.5 | 88 |
| 15 yrs | 76 | 82.5 | 92.3 | 107.2 |