Luvk9s Dog Training

How old is your dog in human years?

Dog owners often use the “seven-year-rule” to calculate their dog’s age in human years - simply multiply your dog’s age by 7. This would make my 13-year-old Labrador retriever 91 years old in human years.

This calculation is not supported by science, so how did this calculation evolve? The most common explanation is that in the early 1950’s, when this calculation became popular, the average life expectancy of a human was about 70 years and canines about 10 years; thus the 7:1 ratio became a logical (and easy) way to calculate a dog’s age in human years.

But new scientific research suggests there is a more accurate way to calculate your dog’s age in human years.      
Why the interest in how dogs age?


​The obvious answer to this question is that having a more accurate estimate of our dog’s age in human years can help us take better care of our senior dogs. Results of recent research by geneticists may also give us new knowledge about how to extend the life of our beloved canines – which may also be applicable to humans.

 Size matters

The American Veterinary Medical Association (AVMA) has determined that different breeds age differently. Based on data collected from veterinary hospitals, pet insurance companies, and breed club surveys, large breed dogs generally have shorter lifespans than smaller breed dogs.

Cornelia Kraus, an evolutionary biologist at the University of Göttingen in Germany, estimates that every 4.4 pounds of body mass reduces a dog’s life expectancy by about one month. Why this is happening is unclear, though the website suggests that “larger dogs may succumb to age-related illnesses sooner and that the accelerated growth of large dogs may lead to a higher likelihood of abnormal cell growth and death from cancer.”

 2019 Epigenetic Clock Study

A team headed up by Tina Wang at the University of California has proposed a far more accurate way of calculating a dogs age by using DNA methylation, a process that occurs in both humans and dogs.

What is DNA methylation? The website has the simplest explanation. “In both dogs and humans, methyl groups are added to DNA molecules throughout aging, altering DNA activity without altering the DNA itself. As a result, DNA methylation has been used by scientists to study aging in humans through an epigenetic clock.”

Epigenetics is the study of how environmental factors cause these adjustments. The website explains that dogs are good models for humans because “they have similar genetics, share our environment and they also have similar diseases and health issues.” By studying how dogs age, we can get a better understanding of how humans age as well.

Wang’s team studied the DNA sequencing in 104 Labrador Retrievers of all ages and compared their “epigenetic clocks” to those of humans.

Based on this new research, the AVMA suggests this updated calculation to estimate a medium-sized dog’s human age:

  • The first year of a dog’s life equals 15 human years.


  • The second year of a dog’s life equals about 9 human years.


  • After that, every five dog years equals about 1 human year.

Note that the actual formula is a bit more complicated. states that the calculation is “the natural logarithm of the dog’s real age, multiplied by 16, with 31 added to the total.”  Click
here to enter your dog's age into the "dog age calculator."

Additional research on other breeds are in the works.

Dog Aging Project

The objective of the Dog Aging Project is to recruit 10,000 pets and their owners to participate in a 10-year study to identify biological and environmental factors that may affect health and longevity. Out of this group, five hundred dogs will be selected to test out a new drug that may help slow down the aging process and may be useful to humans in the future as well.

The goal of the Dog Aging Project is to understand how genes, lifestyle, and environment influence aging and to use that information to help dogs and people increase the period of their life that is spent disease-free.

For more information and/or to register your dog, go to

"Blessed is the person who has earned the love of an old dog."

Sydney Jeanne Seward