How Old Is a 1-Year-Old Dog in Human Years?
| Size | Human age | Life stage |
|---|---|---|
| Small ≤ 9 kg | 15 | Young adult |
| Medium 9–23 kg | 15 | Young adult |
| Large 23–45 kg | 15 | Young adult |
| Giant > 45 kg | 15 | Young adult |
By the veterinary rule of thumb used by the AVMA, a dog's first year equals about 15 human years and the second adds about 9. Size only starts to matter after that, so a 1-year-old dog is about 15 in human years whether it is a Chihuahua or a Great Dane.
A 2020 study from the University of California San Diego compared DNA methylation in 104 Labrador Retrievers with humans and proposed the formula human age = 16 × ln(dog age) + 31. By that formula a 1-year-old dog is about 31. It was derived from a single breed, so it is shown here for comparison rather than as the main estimate.
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How old is a 1-year-old dog in human years?
About 15 human years for a dog of any size.
Is a 1-year-old dog a senior?
Under the simplified AAHA life-stage scheme a dog becomes a senior at about 7 if it is small or medium, at 6 if large and at 5 if giant. At 1: small, medium, large, giant — young adult.
Is one dog year really seven human years?
No. The "×7" rule is a myth: dogs mature much faster in the first two years and then slow down, and large breeds age faster than small ones. By the ×7 rule a 1-year-old dog would be 7; the size-based estimate gives 15.
How do I work out my own dog's age?
Use the calculator on the main dog age page: enter years and months and pick your dog's adult weight. It also covers puppies month by month.