Dog Age Calculator
Convert your dog's age to human years using the modern veterinary formula by breed size — small, medium, or large.
More accurate than the old 7:1 rule.
Dog age in human years is far more nuanced than the old “multiply by 7” rule. Modern veterinary science uses a DNA methylation model developed by researchers at UC San Diego, which better reflects how dogs actually age biologically.
The scientific formula (small/medium breeds):
Human Age = 16 × ln(Dog Age) + 31
Where ln is the natural logarithm.
Simplified reference table:
| Dog Age | Human Equivalent |
|---|---|
| 1 year | ~31 years |
| 2 years | ~42 years |
| 4 years | ~52 years |
| 7 years | ~62 years |
| 10 years | ~69 years |
| 15 years | ~83 years |
This model explains why a 1-year-old dog is sexually mature (equivalent to a young adult), while aging slows significantly in middle and later years — just like humans.
Size correction: Large and giant breeds age faster than small breeds:
- Small breeds (under 20 lbs): Use the formula as-is
- Medium breeds (20–50 lbs): Add 1–2 human years after age 6
- Large breeds (50–90 lbs): Add 3–5 human years after age 5
- Giant breeds (90+ lbs): Add 5–8 human years after age 4 — Great Danes average only 8–10 years of life
Worked example: A 6-year-old Labrador Retriever (large breed): Base: 16 × ln(6) + 31 = 16 × 1.792 + 31 = 59.7 → ~60 human years Size adjustment: +4 years → ~64 human years
Why this matters: Knowing your dog’s true biological age helps you schedule appropriate vet screenings, adjust diet and exercise, and recognize age-related health changes at the right time.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.