"He looked at me with those tawny eyes,
And knew instantly, the truth from the lies.
He had the wisdom of 25 seers combined,
After all, one year of his life was almost 15 years of mine."

No prizes for guessing what I'm talking about. Yes, it's probably the most confusing comparison that we've always tried to understand. It's the dog years to human years ratio. If you're one of those who does not know that how many dog years equal human years, there's nothing to be ashamed of. You have enough company. So read ahead to know the right answer.

Factors Affecting the Ratio of Dog Years to Human Years
Many people (including me, until quite recently) are of the opinion that 1 dog year = 7 human years. Guess what! This is in fact wrong. Read ahead to know how a dog's age is actually calculated and what affects its age.
  • Size of Dog: The size and type of dog matters as far as its age is concerned. A small dog is likely to live longer than a larger dog. They live 1.5 times longer than large dogs.
  • Neutering of Dog: Dog neutering also affects how we compare the ratio. A neutered dog is less prone to prostate cancer, which in turn, increases its life expectancy.
  • Gender of Dog: On an average, female dogs live longer than male dogs. The life expectancy of female dogs is 1-3 years more than males.
  • Breed and Weight of Dog: Comparing dog years to human years by breed is another factor that affects the ratio. Some breeds have a longer life expectancy than others. Light dogs of big breeds live longer than heavy dogs of a smaller breed. For example, an Affenpinscher (small, heavy breed) will live only for about 10-12 years, while a Doberman Pinscher (large, light weight) goes on to live for about 15-20 years.
  • Constitution and Living Conditions: Some dogs, just like humans, have a stronger and more resistant constitution. This has an effect on the life expectancy. Also, proper dog care like how and what it is fed, when and how it is cleaned, vaccinated, etc., play an important part in maintaining its health, preventing illnesses and increasing your dog's life expectancy.
Why is 1 Dog Year 7 Human Years
Given below is a simple explanation of why the ratio of dog years to human years is not 1:7.
  • Dogs mature earlier than humans.
  • A dog matures, both physically and sexually within the first year of being born, as compared to almost 15 years of a human being (general life expectancy being 75 years).
  • This means that it takes the dog 1/5th of the time that it takes a human to mature.
  • So, it's logical to say that the first year of the dog's life is equal to the first 15 years of the human being's (15/75 ).
  • And if we say so, then the remaining 14 years of the dog's life are equal to the remaining 60 years of the human being's life. Which then makes the dog years to human years conversion to 14/60 which comes to around 1/4. This means that every remaining dog year is equal to 4 human years.
Thus, you can see how there is no way 1 dog year = 7 human years.

Dog Years to Human Years Chart

Dog Years Human Years
1 Year 15 Years
2 Years 23 Years
3 Years 29 Years
4 Years 32 Years
5 Years 38 Years
6 Years 40 Years
7 Years 44 Years
8 Years 48 Years
9 Years 52 Years
10 Years 56 Years

*This chart has used the above-mentioned method and assumed the weight of the dog to be approximately 20 lbs.

This was one of the simplest ways to understand the relationship between dog years and human years. Remember, this method only takes into account the life span. For a more accurate calculation, other factors like the ones mentioned above should also be considered. So go ahead, calculate!