Written by Ella White
The most pervasive myth about how dogs age states that one year in human years is the same as seven dog years. But the truth is that dogs mature in a totally different way to humans. So calculating their age compared to our own is complicated, and certainly not as accurate as using the 7:1 method.
How dogs age depends on their breed and size. But in the first one to three years of their life they mature far quicker than one to three year old humans do. So if you’ve ever wondered how old your 6 month old dog is in human years, the answer isn’t so simple!
Rather than aging one year at a time like humans do, dogs develop all the physical and mental functions they need within the first one to three years of their life. Which means that the first year of their life is more like 15 years in human years, with a 6 month old dog being the equivalent of five years old in human years.
After this, their aging process slows down but still remains far ahead of how humans mature. In the second year of their life, a dog ages by about nine human years, and after this point the process evens out to around 5 years for every human year.
The smaller the dog, the longer their life expectancy. So later in life, larger dogs continue to age at a slightly faster rate than their smaller counterparts.
If you ask almost anyone – dog owner or not – how old a dog is in ‘human year,’ the chances are they will calculate their answer using the 7:1 rule which states that one dog year is the equivalent of seven dog years.
There’s no real answer as to where this myth came from, but studies have proven time and time again that it is not an accurate way to measure the maturity of a dog. Some believe that the idea began in the 1950s, when the average human life expectancy was around 70 years old and the average dog’s lifespan was around 10 years. By this logic, one dog year was 7 human years.
The one thing that the theory does get right, however, is the general idea that dogs age much later than humans and therefore a 10 year old dog should be treated as much older than a 10 year old child would be. In fact, large dog breeds are considered senior between the ages of five and six, and small dogs reach seniority at around seven years old.
To understand how your dog is maturing and developing, and to help owners view any health issues that could be arising as their pets grow older, this chart is a handy way to more accurately compare your dog’s age with human years.
It’s not uncommon for dogs to live slightly longer than their expected lifespan if they are given the right care and a happy, healthy lifestyle by their owner. The oldest dog that’s ever lived was Bluey, an Australian Cattle Dog who lived for 29 years and 5 months. In dog years, that’s about 154 in human years! Experts believe that Bluey’s rural life in the country, staying active by working with animals on her owners farm, likely contributed to her long life.