How Old is 9 months in Dog Years?

9 months in dog years roughly equals 10 years 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)

Calculating how many human years is 9 months 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 one dog year equals seven dog years; this assumption was probably first introduced in the 1950s, but it’s not the right way to measure it.

While there has been plenty of research since then disproving this ratio of 7 to 1, it seems people are still holding on the idea. The formula could be based on an assumption that dogs live to 10-ish years and humans can live to 70, however it’s hard to tell when it started.

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

The correct way

The correct way of converting human years into dog years is a bit more complicated.

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

  • The very first year of a medium-sized dog’s life is approximately 15 years human.
  • The second year of a dog’s life is roughly 9 years for humans.
  • From then on, every human year equals the equivalent of four to 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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