Dog Age Calculator
The "multiply by 7" rule is wrong in both directions. Dogs grow up fast in their first two years, and big dogs age faster after that.
How the calculation works
Most vets use a chart based on how dogs mature. The first year equals about 15 human years, and the second adds about 9 more, so a 2-year-old dog is like a 24-year-old person. After that, each year adds about 4 human years for small dogs, 5 for medium, 6 for large and 7 for giant breeds.
A 2020 study of DNA methylation in Labradors proposed a different formula, human age = 16 × ln(dog age) + 31. It fits Labs well but wasn't tested across sizes, so we show it as a second opinion.
Dog years to human years chart
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 | 24 |
| 3 | 28 | 29 | 30 | 31 |
| 4 | 32 | 34 | 36 | 38 |
| 5 | 36 | 39 | 42 | 45 |
| 6 | 40 | 44 | 48 | 52 |
| 7 | 44 | 49 | 54 | 59 |
| 8 | 48 | 54 | 60 | 66 |
| 9 | 52 | 59 | 66 | 73 |
| 10 | 56 | 64 | 72 | 80 |
| 11 | 60 | 69 | 78 | 87 |
| 12 | 64 | 74 | 84 | 94 |
| 13 | 68 | 79 | 90 | 101 |
| 14 | 72 | 84 | 96 | 108 |
| 15 | 76 | 89 | 102 | 115 |
| 16 | 80 | 94 | 108 | 122 |
Frequently asked questions
When is a dog considered a senior?
Around 7 for large and giant breeds, and 10 to 12 for small breeds. Senior dogs benefit from vet checkups twice a year.
Why do big dogs age faster?
Nobody knows for sure, but large breeds grow very fast and tend to develop age-related disease earlier. A Great Dane's typical lifespan is 8 to 10 years; a Chihuahua's is 14 to 16.