Dog Care
Dog Years to Human Years: Chart by Size (and Why It's Not 7)
How do you convert dog years to human years? A medium-sized dog's first year equals about 15 human years, the second year adds about 9 (so 24 at age two), and each year after that adds about 5. Small dogs age a little slower after that and large dogs a little faster, so size matters more than the old "multiply by 7" rule.
Dog years to human years chart
Approximate human-age equivalents. Years 1 and 2 are the same for every size; after that we add about 4 years per year for small dogs, 5 for medium and 6 for large.
| Dog's age | Small (under 20 lb) | Medium (20–50 lb) | Large (over 50 lb) |
|---|---|---|---|
| 1 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 |
| 3 | 28 | 29 | 30 |
| 4 | 32 | 34 | 36 |
| 5 | 36 | 39 | 42 |
| 6 | 40 | 44 | 48 |
| 7 | 44 | 49 | 54 |
| 8 | 48 | 54 | 60 |
| 9 | 52 | 59 | 66 |
| 10 | 56 | 64 | 72 |
| 11 | 60 | 69 | 78 |
| 12 | 64 | 74 | 84 |
| 13 | 68 | 79 | 90 |
| 14 | 72 | 84 | 96 |
| 15 | 76 | 89 | — |
| 16 | 80 | 94 | — |
The 15 + 9 + 5 pattern for a medium dog is the guideline the American Kennel Club attributes to the American Veterinary Medical Association. The small and large columns are our approximation of the size effect, so treat them as a rough guide.
Quick answers
- 1 dog year is about 15 human years.
- 4 years in dog years is about 32–36, depending on size.
- 5 years in dog years is about 36–42.
- 10 years in dog years is about 56–72.
- 13 years in dog years is about 68–90.
Why the "1 dog year = 7 human years" rule is wrong
The multiply-by-7 rule is decades old and doesn't match how dogs age. Dogs mature very fast in their first two years, then age more steadily, and big dogs age faster than small ones. That's why a 1-year-old dog can have puppies, which a 7-year-old child obviously can't.
The DNA "epigenetic clock" formula
A 2019 study from the University of California San Diego compared DNA changes in 104 Labrador Retrievers with humans and proposed: human age = 16 × ln(dog age) + 31. By that formula, a 1-year-old dog is about 31, a 2-year-old about 42, a 4-year-old about 53, a 7-year-old about 62 and a 10-year-old about 68. It's interesting, but it was based on one breed, so the chart above is the more practical guide.
When is a dog a senior?
Large and giant breeds are often considered seniors at around 5 to 7, and small breeds later, around 8 to 10 or beyond. See our senior dog age chart by size.
Frequently asked questions
How old is my dog in human years?
For a medium dog: 15 at age one, 24 at age two, then add about 5 per year. Small dogs add about 4 a year after two, large dogs about 6.
How many dog years are in one human year?
It changes with age. The first year counts for about 15, the second for about 9, and later years for about 4 to 6 depending on size.
How old is a 10 year old dog in human years?
About 56 for a small dog, 64 for a medium dog and 72 for a large dog.
Is there a dog years calculator?
Use the chart above for dog years. For typical lifespan, life stage and estimated time left together, try our free pet lifespan calculator.
What about cat years?
Cats age differently. See cat years to human years.
Sources
Guidance follows the American Kennel Club, including its summary of the 2019 UC San Diego study. This article is general information, not veterinary advice.
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