The DNA-based dog age formula
In 2020, researchers at the University of California San Diego compared age-related changes in DNA (methylation) between Labrador retrievers and people, and found dogs age very fast early in life and slow down later. Their formula:
"ln" is the natural logarithm. Example: a 4-year-old dog is 16 × ln(4) + 31 = 16 × 1.386 + 31 = about 53 human years. A 1-year-old dog is like a 31-year-old, because ln(1) = 0.
Why "times seven" is wrong
The 1 dog year = 7 human years rule makes a 1-year-old dog a 7-year-old child, yet most dogs can have puppies before their first birthday. The DNA formula matches real life stages better: an 8-week-old puppy is like a 9-month-old baby teething, and a 10-year-old dog is in its late 60s.
Limits: the study used one breed. Large breeds tend to age faster and have shorter lives than small breeds, so a Great Dane may be "older" than this estimate and a Chihuahua "younger".
Next steps
For people, the age calculator gives an exact age to the day, and the date difference calculator counts the days until your dog's next birthday.
Frequently asked questions
How old is my dog in human years?
Use 16 × ln(dog's age) + 31. A 2-year-old dog is about 42, a 7-year-old about 62, and a 12-year-old about 71.
Is 1 dog year really 7 human years?
No. Dogs mature much faster than that in their first two years and age more slowly after. A 1-year-old dog is closer to a 31-year-old adult.
Does dog size change its age in human years?
Yes. Large breeds generally age faster and live shorter lives than small ones, so treat the result as an average.
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