PuppyGrowthHow dog years are calculated
Dogs mature very fast at first: a 1-year-old dog is roughly like a 15-year-old teenager, and a 2-year-old like a 24-year-old adult. After that, how fast they age depends on size. Small dogs age more slowly and live longer; giant breeds age fastest.
After that, per year: small +4 · medium +4.5 · large +5.3 · giant +7
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 | 24 |
| 5 | 36 | 38 | 40 | 45 |
| 8 | 48 | 51 | 56 | 66 |
| 10 | 56 | 60 | 67 | 80 |
| 12 | 64 | 69 | 77 | 94 |
| 14 | 72 | 78 | 88 | 108 |
This is a widely used size-based approximation. Newer research based on DNA changes suggests puppies age even faster early on; any human-age figure is a comparison, not a medical measurement.
Frequently asked questions
Is one dog year really 7 human years?
No. That rule is an old simplification. Dogs age much faster in their first two years and then at a speed that depends on size.
How old is a 10 year old dog in human years?
About 56 for a small dog, 60 for a medium dog, 67 for a large dog and 80 for a giant breed.
When is a dog considered senior?
Giant breeds around 5–6 years, large breeds around 6–7, and small and medium breeds around 7–8 years.
More free pet calculators
PuppyGrowthCalc gives general estimates for healthy pets. Every animal is different. Ask your vet about your pet's ideal weight, diet and health.