# Dog Years to Human Years: How Do They Actually Work?

Like many animal-loving children, I grew up believing that I could accurately calculate my dog’s age in human years by following this simple rule: one dog year equals seven human years.

It was nice, easy math for a kid, which was great because it meant I could get the answers I needed quickly and I could practice my multiplication. You’ve probably heard this rule before too, and so I have to warn you that the following information could come as an unpleasant surprise.

Dog years are not that simple.

As it turns out, dogs don’t age according to mathematical convenience, which starts to make sense once you see the numbers.

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.

Sound simple enough?

Don’t get too excited.

It gets a little more complicated. 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.

This means that any calculation about dog to human years needs to account for size too. The AKC has a helpful chart that breaks this information down for every year. The AVMA on the other hand takes a broader approach.

• 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.

So the next time you try to calculate a dog’s age in human years, remember that the old rules no longer apply and follow these guidelines instead.