How to Calculate Your Dog's Age in Human Years

A new way to convert dog years to human years
By Claudia Kawczynska, November 2019
Labrador breed dog used in dog age study

Researchers have come up with a new, and more accurate way, to tell how old your dog is compared to human years. The formula that many of us are familiar with was based on a simple calculation of one dog year equaling seven human years.

This new approach to determining a dog's age is a lot more accurate and is based on the actual chemical modifications to a person’s (human or dog) DNA over a lifetime that create an epigenetic clock.

The Science Behind a Dog's Age

Dogs and humans, along with many other species undergo a DNA methylation process as they age. A team of scientists from the University of California, San Diego who are studying aging and how these clocks differ across species, started their research with dogs. “Although humans and dogs diverged early during mammalian evolution dogs share nearly all aspects of their environments with humans. These include, critically for these studies, similar levels of health observation and health care intervention.” Their assumption is that all dogs, regardless of breed, follow a similar developmental trajectory, with puberty reached at 10 months and dying before 20 years. The team focused on Labrador Retrievers, because they were hoping to increase their chances of finding genetic factors associated with ageing by concentrating on just one breed.

The researchers found “that this function showed strong agreement between the approximate times at which dogs and humans experience common physiological milestones during both development and lifetime aging, i.e. infant, juvenile, adolescent, mature, senior.” This translates into a seven-week-old pup equaling that of a nine-month-old child—a time by which deciduous teeth erupt in both pups and babies. They did find that dogs and humans do have similar age-related methylation of certain genomic regions, especially during aging in both species.


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How Old is My Dog?

The team also developed a new epigenetic clock and a formula for calculating it. The dog’s age must be greater than one year, then that dog age is converted into a natural logarithm and that log is multiplied by 16, and then 31 added for a total. For example, if a dog is 14 years old, the natural log of 14 is 2.6390, multiplying that by 16 equals 42.224, adding 31 brings it to 73.2. That's a lot of math! See our dog age calculator and our dog year chart for easy reference.

full dog age chart details from dog age calculator

Dog Years to Human Years

In previous study, researchers found a way to calculate a dog's age, while taking size and breed into consideration too since small dogs tend to live longer. In that 2013 study they determined that small dogs age on average 12.5 years per human year, compared to 9 years for large dogs. According to this model, a Miniature Dachshund will age on a 4 to 1 human years scale whereas a Bulldog will age an average of 13 years per human year. If you adopted a dog of unknown age, we've compiled some tips to help find out a dog's age even if you don't know their birthday based on phsyical factors like teeth, eyes, fur, and muscle mass.

Recently, an article in Science about this research also mentioned another group that is studying the aging process of dogs, called Dog Aging Project. It is currently collecting data from pet dogs of citizen scientists. The goal of this project is to understand how genes, lifestyle, and environment influence aging and is a collaborative effort of the University of Washington and Texas A&M University. They hope to see why some dogs develop diseases at younger ages and die earlier, while others like, hopefully, my 14-year-old Lola, lead a mostly disease-free life. I always knew that Lola and I had much in common, that now includes having similar epigenetic ages (see the above calculation).

Photo: ryniu1234 / Pixabay