Dog Age Calculator — Dog Years to Human Years
Convert your dog's age to human years using the updated non-linear formula that accounts for breed size. The old "multiply by 7" rule is inaccurate. See also our Cat Age Calculator and Age Calculator.
How to Calculate Dog Age in Human Years
- Enter your dog's age in years.
- Select your dog's breed size category.
- Click Calculate to see the human equivalent age.
- The first year equals about 15 human years for all sizes.
- After year 2, aging rate depends on breed size (larger dogs age faster).
Formula
Year 1: +15 human years (all sizes)
Year 2: +9 human years (all sizes)
Year 3+: +4 to +7 human years per dog year
Small: +4-5/year, Medium: +5/year
Large: +6/year, Giant: +7/year
Example
Dog: 5 years old, Medium breed
Year 1: 15, Year 2: +9 = 24
Years 3-5: +5 each = +15
Result: 24 + 15 = 39 human years
Dog Age to Human Age Reference Table
| Dog Age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 | 24 |
| 3 | 29 | 29 | 30 | 31 |
| 5 | 39 | 39 | 42 | 45 |
| 7 | 48 | 49 | 54 | 59 |
| 10 | 60 | 64 | 72 | 80 |
| 13 | 72 | 79 | 90 | 101 |
| 15 | 80 | 89 | 102 | 115 |
Frequently Asked Questions
Why is the 7-year rule wrong?
Dogs mature much faster in their first two years (reaching adulthood by age 2), then age more slowly. The 7x rule oversimplifies this non-linear aging process.
Why do large dogs age faster?
Larger dogs have shorter lifespans, possibly due to faster growth rates putting more strain on their bodies. Giant breeds may only live 7-10 years while small breeds can reach 15-20.
At what age is a dog considered senior?
Small dogs: 10-12 years, Medium dogs: 8-10 years, Large dogs: 6-8 years, Giant dogs: 5-6 years. Senior dogs need more frequent vet checkups.
What is the oldest dog ever recorded?
The oldest verified dog was Bobi, a Portuguese Rafeiro do Alentejo who lived to 31 years and 165 days (2023). Previously, Bluey, an Australian Cattle Dog, held the record at 29 years.
How can I help my dog live longer?
Regular vet visits, proper nutrition, daily exercise, dental care, maintaining a healthy weight, and mental stimulation all contribute to canine longevity.