CollarDog Age Calculator: Dog Years to Human Years
How old is your dog, really? Convert your dog's age into human years with the modern veterinary formula, and see her life stage and typical lifespan for her size.
Dog Age Calculator
Enter your dog's age to convert it into human years.
How to Calculate Dog Years in Human Years
Forget the old “one dog year equals seven human years” rule: it is a myth. Dogs grow up very quickly, then age more slowly. Veterinarians use this formula instead:
- Year 1 counts as about 15 human years.
- Year 2 adds about 9 more (roughly 24 human years by age 2).
- Each year after adds about 5 human years.
Human age ≈ 15 + 9 + (dog years − 2) × 5
Why Size Matters
Small dogs live longer and stay “younger” later in life, while large and giant breeds age faster. That is why this calculator also shows a life stage and a typical lifespan based on your dog's size.
Enter her age
Give your dog's age in years or months.
Pick her size
Size changes the life stage and expected lifespan.
See her human age
Get her age in human years, life stage, and lifespan.
Dog Age to Human Age Chart
A quick conversion using the modern veterinary formula. Larger breeds may age a little faster in their senior years.
| Dog age | Human years | Dog age | Human years |
|---|---|---|---|
| 1 year | 15 | 9 years | 59 |
| 2 years | 24 | 10 years | 64 |
| 3 years | 29 | 11 years | 69 |
| 4 years | 34 | 12 years | 74 |
| 5 years | 39 | 13 years | 79 |
| 6 years | 44 | 14 years | 84 |
| 7 years | 49 | 15 years | 89 |
| 8 years | 54 | 16 years | 94 |
Frequently Asked Questions
Answers to the most common questions about your dog's age.
The modern veterinary formula counts the first year of a dog's life as about 15 human years, the second year as about 9 more (roughly 24 human years by age 2), and each year after that as about 5 human years. So a 5-year-old dog is roughly 39 in human years.
No. The old rule of 7 human years per dog year is a myth. Dogs mature very fast in their first two years and then age more gradually. That is why the first year alone counts for about 15 human years.
Yes. Small dogs live longer and become seniors later (around 10 to 11 years), while large and giant breeds age faster and are often considered seniors by 6 to 7 years. Giant breeds typically live 8 to 10 years, small breeds 14 to 16.
It depends on size. Small dogs are usually seniors around 10 to 11 years, medium dogs around 8 to 10, large dogs around 7, and giant breeds as early as 5 to 6 years old.
Sources & Further Reading
The formula and lifespan figures on this page reflect published veterinary averages. To go deeper, visit these trusted references: