Dog Age Calculator
Convert dog years to human years with a size-aware chart: 15 the first year, 9 the second, then about 4–7 human years per year.
How to use this dog age calculator
The “multiply by 7” dog-age myth overstates puppies and understates giant breeds. A common veterinary-style chart uses 15 human years in year one, 9 in year two, then 4–7 per year depending on size because large dogs age faster after adulthood.
This is a curiosity chart, not a health span or a reason to skip the vet. Mixed breeds: pick the size they actually are, not the largest ancestor. Months let you land between birthdays.
Formula
Worked example
A 5-year-old medium dog is about 24 + 3 × 5 = 39 human years. A giant breed the same age is older on the chart.
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Frequently asked questions
How do I calculate dog years to human years?
15 the first year, 9 the second, then about 4–7 per year by adult size — not ×7 every year.
Is 1 dog year 7 human years?
No. That rule is too crude. Puppies mature faster than 7×; giant dogs age faster later.
Do small dogs live longer?
Often yes, which is why their later years add fewer human years per calendar year on this chart.
What about mixed breeds?
Use current adult weight class, not a DNA pie chart.
Is this a veterinary diagnosis?
No. Use it for birthdays and small talk. Dental, weight, and labs matter more.
Results are estimates for informational purposes and are not financial, legal, or professional advice. Last reviewed 2026-08-20.