How Old is 1 in Dog Years?

Last Updated on December 4, 2022 by Becky Roberts

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)

1 in dog years

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 way

Most people still assume that 1 dog year equals 7 dog years. This belief was probably first introduced in the 1950s. However, this isn’t the best way to measure it.

Although there’s been quite a bit of research since then disproving the 7:1 ratio, people are still holding on the idea. The formula could have been based on the assumption that dogs live to 10-ish years and humans reach 70 years old, but honestly, we’re not quite sure when it started.

So while the 7-1 rule is easy to calculate and remember, it’s unfortunately incorrect.

The correct way

The best method of converting human years to dog years is a bit more difficult.

The American Veterinary Medical Association has the following to say about it::

  • The beginning year of a medium-sized dog’s lifespan equals around 15 human years.
  • The second year in a dog’s lifespan is roughly 9 years for humans.
  • From that point forward each year of a human equals either four or five dogs 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.


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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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