How to Calculate Your Dog’s Age in Human Years

Maybe your 15 year old Chihuahua still acts like a teenager or your two year old Great Dane is an old soul. But what is your dog’s age in human years? Turns out, we may have been barking up the wrong proverbial tree with the formula that many of us are familiar with — the simple calculation of one dog year equaling seven human years. Researchers have come up with a new — potentially more accurate — way to estimate how old your dog is compared to human years. 

This revised approach to determining a dog’s age is based on the actual chemical modifications to a creature’s (human or dog) DNA over a lifetime that create an epigenetic clock — that’s a biochemical test that can be used to measure age.

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.

How Old Is My Dog?

The team also developed a new epigenetic clock and a formula for estimating a dog’s age in human years. Your pup’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 for pet parents! 

How to Translate Dog Years To Human Years

In a previous study, researchers found a way to calculate a dog’s age, while also taking size and breed into consideration 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, you can determine a dog’s age even if you don’t know their birthday based on physical factors like teeth, eyes, fur, and muscle mass.

Recently, an article in Science about this research mentioned another group that is studying the aging process of dogs, called the Dog Aging Project, a collaborative effort of the University of Washington and Texas A&M University. It is currently collecting data from pet dogs of citizen scientists to understand how genes, lifestyle, and environment influence aging. They hope to understand why some dogs develop diseases at younger ages and die earlier, while others lead a mostly disease-free life.