Dog Age Chart
Dog years to human years, broken out by adult size — because a 10-year-old Great Dane and a 10-year-old Chihuahua are not the same "age."
Dog age chart by size
The first two years are roughly the same across all sizes — dogs mature quickly early on. After that, larger dogs age faster than smaller ones. Numbers below are approximate human-year equivalents.
| Dog's age | Small (up to 20 lbs) | Medium (21–50 lbs) | Large (51–90 lbs) | Giant (over 90 lbs) |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 |
| 3 years | 28 | 29 | 29 | 30 |
| 4 years | 32 | 33 | 34 | 36 |
| 5 years | 36 | 38 | 39 | 42 |
| 6 years | 40 | 42 | 44 | 48 |
| 7 years | 44 | 47 | 49 | 54 |
| 8 years | 48 | 51 | 54 | 60 |
| 9 years | 52 | 56 | 59 | 66 |
| 10 years | 56 | 60 | 64 | 72 |
| 12 years | 64 | 69 | 74 | 84 |
| 15 years | 76 | 83 | 89 | 102 |
Why the columns spread apart over time
Small breeds tend to add around 4 human years per dog year after age two, while giant breeds add 6 or more. It's a well-documented pattern in veterinary aging research — larger dogs grow faster as puppies, but that same growth rate seems to carry a cost later, showing up as earlier aging and shorter average lifespans.
Want an exact number instead of a chart?
This chart uses rounded whole-year steps. For your dog's precise age, including fractional years, use the Dog Age Calculator — it runs the same size-based formula behind this chart. For the reasoning behind the formula itself, see How Old Is My Dog in Human Years?, or if your dog is under two, see Puppy Age in Human Years.