Dog Years to Human Years Converter
One dog year is not seven human years. Dogs race through the equivalent of 15 human years in their first year, hit about 24 by age two, and then slow to a pace set by their adult size. Enter your dog's age and size below to convert dog years to human years the way vets actually do it.
Choose the size your dog will reach when fully grown. Always use adult size, even for a puppy. A Great Dane puppy is Giant from day one.
How to Convert Dog Years to Human Years
The conversion vets use takes three steps:
- Count the first dog year as 15 human years.
- Count the second dog year as 9 more (24 human years total).
- For every year after that, add 4 for a small dog, 5 for a medium dog, 6 for a large dog, or 7 for a giant breed.
A few quick examples: a 3 year old medium dog is about 29 in human years. A 7 year old large dog is about 54. A 10 year old small dog is about 56, while a 10 year old giant breed is already around 80 — the size gap grows every year after age two.
Partial years count too. A dog of 3 years 6 months sits halfway between the year-3 and year-4 values, which is exactly how the converter above handles months.
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 |
For a deeper look at the table — including how to pick the right size column and what the numbers mean for senior care — see the full dog age chart page, or read the science behind the numbers on the main dog age calculator page.
Frequently Asked Questions
There is no single multiplier. The first dog year equals about 15 human years, the second adds 9 more (24 total), and every year after that adds roughly 4 to 7 human years depending on the dog’s adult size.
Count 15 human years for year one and 24 by the end of year two, then add 4 per year for small dogs, 5 for medium, 6 for large, or 7 for giant breeds. The converter above does the math for you, including partial years.
Body mass is closely tied to lifespan in dogs. Smaller dogs tend to live longer and age more slowly after the first two years, while large and giant breeds age faster — a 10 year old small dog is about 56 in human years, but a 10 year old giant breed is closer to 80.
No. Both species mature quickly in their first two years, but the year-by-year pace afterwards differs, and dog aging varies strongly by size while cat aging does not. Use a species-specific chart for each.