It’s been a long-held modern belief that your pup ages seven years for every human year. Now, no one really knows where this “ratio” came from. But the consensus is that humans used to average a 70-year lifespan, and dogs would average 10.

Experts now say that this belief is wrong. Why? Because there are several complex factors that determine your pooch’s accurate “human age”

For example, dogs age far more quickly at the beginning of their lives, and then much more slowly toward the end. or instance, dogs can reach full sexual maturity, and are able to breed, at just one year of age.1 Humans, on the other hand, tend to age fairly consistently.

So, how old is your dog in human years? Perhaps the most important factor for determining your dog’s age is …

Breed Size

Dog's Age In Human Years | Dr MartyA canine’s breed has a great influence on both their size and their lifespan. Small dogs tend to mature faster and live longer than larger dogs. So, a small pup who’s been alive for five years isn’t necessarily the same “age” as a larger breed who is also five years old. Yes, their chronological age is the same, but in terms of their physical age, there are variances.

Why larger dogs seem to die younger is still a bit of a mystery. But according to a study in Inside Science, scientists have come to the conclusion that every 4.4 pounds of body mass reduce a dog’s life expectancy by around one month.

Here’s the thing: They don’t know why. They give the example of a 150 lb. Great Dane, which will only live for about seven human years, compared to a 9 lb. poodle, whose average lifespan is double that, at around 14 years.

So, what’s classified as a small or large dog?

According to the American Veterinary Medical Association:

  • A small dog is 0-20 lbs.
  • A medium-sized dog is 21-50 lbs.
  • A large dog is 51 – 90lbs
  • A very large dog is considered 90 lbs. and above.

The AVMA also considers a small pup to be hitting the golden years at around seven years of age, while larger breeds are considered senior citizens at around 5-6 years.3

How To Do The Math

As a general guideline, it’s usually broken down like this:

  • The first year of a medium-sized dog’s life = approximately 15 human years
  • The second year for a dog = approximately nine human years
  • From then on, every human year would be approximately five years for a dog.4

So, as you can see, the math is a bit more complicated than just “multiplying by seven” to get your dog’s age in human years. But there are easy conversion charts available, which take breed size into account, like this one on The American Kennel Club’s website.

How Can I Ensure That My Pooch Lives A Long Life?

The only thing that we have control over when it comes to our beloved pet’s lifespan is ensuring that they’re well cared for and well loved. Dogs can still be happy, healthy, and agile in their senior years – if they’re properly looked after.

This means:

  • Dog's Age In Human Years | Dr MartyRegular trips to your veterinarian for checkups and vaccinations
  • A healthy diet
  • Watching their weight – obesity in pets (like humans) can shorten their lifespan
  • Plenty of exercise
  • Keeping their minds active with activities, puzzles, and attention
  • Good dental hygiene
  • Keeping their environment stress-free
  • Being acutely aware of any changes in your dog

Age is Only a Number

At the end of the day, for both humans and dogs — age is only a number. And that number is NOT the most important thing. Age is more about how old your dog feels. Because as long as your pup is healthy and happy, the number really doesn’t matter.

If you ensure that your pet is protected against disease, eats a nutritious diet, gets plenty of exercise, visits your vet on a regular basis, and is showered with love – then they really are living the best quality life possible!


Learn More:
The 6 Smartest Dog Breeds
6 Tips for Summertime Dog Safety (paws included!)
Have a Fat Dog? (what causes obesity in dogs and how to fix it)