The American Veterinary Medical Association states that the first year of a medium-size dog’s life is about 15 human years. In other words, your dog goes from sweet puppy to bratty teenager all within that first year, which most puppy owners can attest to. The second year of your dog’s life is the equivalent of nine human years, putting them into young adulthood and hopefully a little more maturity. After that, it is relatively safe to estimate about five human years for every dog year.
You may have noticed that the AVMA used the term “medium-size” dog in their calculations. That is because the size of your dog’s breed plays a large role in determining their age in human years. For instance, a small dog can live almost twice as long as a big dog, but conversely, they tend to mature more quickly. Big dogs on the other hand mature more slowly as puppies, but then age at an accelerated rate as adults when compared to smaller breeds.
A 7-year-old dog, by the AVMA’s reckoning, is anywhere from 44 to 56 years old. A small dog would be closer to 44, while a big dog, would be closer to 56.
A 10-year-old dog is 56 to 78 in human years.
A 15-year-old dog is 76 to 115 in human years.
And for those dogs that make it to 20, they would have lived a human life span of 96 to 120 years — pretty impressive.