The Truth About Dog to Human Age Conversion

Learn how to convert your dog’s age to a human age.

You might have heard the common saying that a dog ages 7 human years for every calendar year they live. That's not exactly right, though. It's quite a bit more complicated. Here's the real scoop.

Dogs Hit Puberty Early

As you know if you've ever raised a puppy, the first year brings a tremendous amount of growth and change. In fact, by the end of their first year, a dog is equivalent physically to about a 15-year-old person. Dogs go through their version of puberty around 6 to 8 months of age. Female dogs have their first heat then and are able to breed. By around 7 months of age, all of a dog's adult teeth are in.

The First 5 Years of a Dog's Life

After the first year, aging slows down a little, and by 5 years of age, dogs are the equivalent of around 36 human years old. That's still pretty close to the old adage that 1 year equals 7 human years for a dog. But after 5 years, canine aging differs depending on whether you are talking about a small, medium, or large breed dog.

The Difference in Aging for Small, Medium, and Large Dogs

Small dogs live longer than large or giant ones, and that translates to slower aging relative to human years once the first 5 calendar years are over. Small dogs age the equivalence of around 4 years per year, medium dogs range from 5-7 per year, and large dogs age from between 5 and 9 human years per one calendar year.

What this all means is that if a dog lives to be 15 years old, his human age equivalence is:

This can all be slightly confusing, and of course, there is some variation among breeds within the general size ranges. Giant breed dogs, for instance, have an average lifespan of 7-10 calendar years.

Here's a basic chart to give you an idea of the human age equivalent for a dog in the three main size ranges of small, medium, and large.

(Mansourian, 2015)
Size of Dog Small Medium Large
Age in Years Human Age Equivalent Human Age Equivalent Human Age Equivalent
1 Year 15 15 15
2 Years 24 24 24
3 Years 28 28 28
4 Years 32 32 32
5 Years 36 36 36
6 Years 40 42 45
7 Years 44 47 50
8 Years 48 51 55
9 Years 52 56 61
10 Years 56 60 66
11 Years 60 65 72
12 Years 64 69 77
13 Years 68 74 82
14 Years 72 78 88
15 Years 76 83 93
16 Years 80 87 120

How to Help Your Dog Live a Longer and Healthier Life

Now that you know about what human age your dog is equivalent to, you might be wondering how you can help your dog live longer and stay healthier. Here are some general tips and links to articles with more information:

Works Cited

  1. Mansourian, E. (2015, Nov. 17). How to Calculate Dog Years to Human Years. Retrieved from

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