How Many Human Years Is My Dog?

It's safe to say every owner, at some point, compares their dog's age to their own. The most widespread idea is that each dog year equals one human year.

But the truth is this calculation, at minimum, has significant variations. Both growth and aging processes are very different depending on the dog's size. Want to know how many human years your dog is? We show you below.

The Multiply-by-Seven Rule for Calculating Dog Years

The most well-known formula for equating dog and human age is multiplying the dog's years by seven. So, when our puppy grows and turns one year old, it'd be blowing out seven candles if it were a child.

A five-year-old adult dog would be, as a person, roughly thirty-five. Meanwhile, a senior dog that's reached ten years old would be the equivalent of a seventy-year-old.

But anyone who's paid even a little attention to more dogs than their own will notice a ten-year-old German Shepherd isn't the same as a ten-year-old Pekingese. So, although it's a very widespread rule, there are reasons to question whether the seven-to-one ratio is actually valid.

Formula for Calculating Your Dog's Human Age

The formula proposed in the study mentioned states that a dog's human age equals 16ln(dog's age) + 31. In other words, this means calculating 16 times the natural logarithm of the dog's age, plus 31.

Better to use a calculator: enter your dog's age and press the ln key. Multiply by 16 and add 31. If you don't have a scientific calculator handy, here's the result of this calculation:

• 1 dog year = 31 human years
• 2 dog years = 42.1 human years
• 3 dog years = 48.6 human years
• 4 dog years = 53.2 human years
• 5 dog years = 56.8 human years
• 6 dog years = 59.7 human years
• 7 dog years = 62.1 human years
• 8 dog years = 64.3 human years

From 9-10 years old, a dog is considered senior/elderly, depending on its size (small dogs live more years)

• 9 dog years = 66.2 human years
• 10 dog years = 67.8 human years
• 11 dog years = 69.4 human years
• 12 dog years = 70.8 human years
• 13 dog years = 72 human years
• 14 dog years = 73.2 human years
• 15 dog years = 74.3 human years

Science Says How Old Your Dog Is

Science has also examined dogs' age compared to humans'. In fact, there's a recent published study on this that disproves the popular seven-year rule. Its authors have concluded dogs are older than previously thought, at least early in their life.

To reach this hypothesis, they based their work on observing chemical changes in DNA that appear as the dog ages. Specifically, they studied changes in "methylation marks," which appear as years pass. To do this, they looked at 104 Labrador dogs from a few weeks old up to 16 years old.

They compared methylation changes with humans' and arrived at a mathematical formula that more accurately matches human and canine life stages. According to their calculations, a 2-month-old puppy would be like a 9-month-old human baby. A Labrador's 12 years would correspond to 70 years in humans.

The Aging Process in Dogs

Generally, dogs' aging mechanisms are similar to humans'. So, just as happens to us, susceptibility to various illnesses increases with age — although not always fatal, these do impact quality of life.

Veterinary care, which has expanded to reach more and more dogs in our societies, is helping more dogs live more years with an acceptable quality of life. Also, advances in veterinary medicine have expanded the list of illnesses that can be treated.

Specialized diets, specific medications, diagnostic tests, or surgical techniques let dogs be successfully treated for conditions that just a few years ago had no solution. All this also allows for better study of older dogs and, as a result, their aging process.

Canine Molecular Growth

In the study by Wang and eleven other scientists, it was determined that dogs age at the molecular level very quickly at first, though later at a slower pace. This can be seen through an easily visible example: sexual maturity.

Simplifying, we can identify this with the appearance of the first heat cycle. Practically every dog breed, except giant-sized ones, can successfully reproduce and bring their first litter into the world before turning a year old.

So, it's not realistic to hold onto the idea that a one-year-old dog would be a seven-year-old human. Scientists offer a very different, more realistic equivalence based on the data: a one-year-old dog would be roughly in its thirties if it were human.

The Importance of a Dog's Age

Establishing as accurate a comparison as possible between dog and human age isn't just a pastime to know how many human years our dog would be. It also helps preventive veterinary medicine.

With this data, it's possible to plan actions aimed at improving a dog's quality of life and extending its life expectancy. That's why continuing research across different dog breeds is important.

Bibliography Wang et al. (2020): "Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome."