How Old is 1 in Dog Years?

1 in dog years roughly equals 15 in human years.

This calculation was made for a medium-sized dog (21 to 50 pounds) using the recommendations from the AKC (American Kennel Club).

There are 2 ways of calculating the conversion from human years to dog years. The above result was calculated using the more correct way, we’ll explain what makes the other way incorrect later in this article.

The table below shows dog years and their equivalent to human years, with different columns for different sizes.

Dog's Age in YearsHuman Years (Small Dog)Human Years (Medium Dog)Human Years (Large Dog)

How Old is 1 in Dog Years? 1

Calculating how many human years is 1 in dog years

As mentioned above, there are 2 main ways of calculating dog years to human years and vice versa. There’s a correct way and an incorrect way.

The old calculation

Most people still assume that 1 dog year equals seven dog years. This assumption likely began in the 1950s, but it’s not the correct method of calculating it.

There has been quite a bit of research since then disproving this ratio of 7 to 1, it seems that people still believe in it. The formula could have been based on the idea that dogs live to 10 or so years, and humans live to 70, but honestly we don’t know the date it was first introduced.

Therefore, while the 7-1 rule is easy to calculate and remember but it’s not the best idea.

The new way

The best method of converting human years to dog years is more complex.

The American Veterinary Medical Association has the following things to be said about it:

  • The first year of a medium-sized dog’s life is approximately 15 years human.
  • The second year of a dog’s existence is equivalent to 9 human years.
  • From that point onwards each human year is equal to four or five dog years.

Keep in mind that smaller dogs tend to live longer than bigger dogs. Scientists concluded that every 4.4 pounds of body mass reduced a dog’s life expectancy by about a month.


Becky Roberts

Becky Roberts

One of Becky's favourite things to do every morning is to browse the top pet-related forums, looking for issues and questions that people have. She then shortlists the most common ones, and turns them into blog posts for Fuzzy Rescue. She's had over 4 cats and 2 dogs over the past decade, so she does know a thing or 2 about raising/training, and more importantly, loving them. She's the only one on our team that doesn't like coffee, but it seems to us she really doesn't need more energy :). We're very fortunate to have her on board as she does most of the heavy listing for the site, outputting an insane amount of content each month. Read More

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