Have you ever wondered how old your dog is in human years? Most people ask this question and use the standard calculation method of “one dog year is equal to seven human years” to calculate the age. However, the age that is derived using this method is not accurate, as it is more of an urban legend than a legitimate way to calculate a dog’s age in human years.
So why has the 7:1 formula been around for so long? One possible reason is that when the formula was first popularized, the average human lifespan was roughly 70 years, while the average dog lifespan was 10 years. Therefore, 10 dog years was determined to be equal to 70 human years, which means that 1 dog year is equal to 7 human years.
However, we now know a lot more about how to correctly determine a dog’s age in human years, and we know that a variety of factors influence this age, including breed, size, and genetics.
How to calculate dog age in human years? Let’s take a 6-year-old dog as an example – that would be 40 to 49 years old in human years. Here’s how it works!
| size: | Human age: |
| Small dogs (under 20 pounds): | 40 years |
| Medium dogs (21-50 lbs): | 42 years |
| Large Dogs (51-100 lbs): | 45 years |
| Large breeds (over 100 lbs): | 49 years |
sauce: AKC
How to convert dog years to human years
Converting dog years to human years requires a bit more math than simply calculating a 7:1 ratio these days: According to an article by the AKC, the American Veterinary Medical Association, a dog’s first year of life is equivalent to 12 to 15 human years, and the second year is equivalent to 9 to 10 human years.1 From the dog’s third year onwards, one year equates to about four to five human years, although this figure varies based on the size of the dog.
Small dogs
Small dogs live longer than large dogs, but the reasons for this are not entirely clear. That means that the calculation of the human years of a small dog puppy is a bit different than for a large dog. A small dog’s first year is about 15 human years. In its second year, it reaches about 24 human years, and in its third year, it reaches about 28 human years. This means that a 6-year-old small dog is about 40 human years.
Medium-sized dogs
Medium dogs age a little faster than small dogs, so calculating their age is similar to calculating their age for small dogs. In fact, the first three years of a medium dog’s life are equivalent to 15, 24, and 28 human years. However, once a medium dog reaches about 6 years of age, they start aging faster. So, a medium dog will be 42 human years old when he turns 6 in dog years.
Large dog
For larger dogs, the situation is different because they age faster than small and medium dogs. However, by the time they reach 6 years of dog years, they will most likely start aging sooner. So, when they reach 6 years of dog years, they will be 45 years old in human years, which is relatively close to the age of small and medium dogs.
Giant species
Large breeds age faster than other breeds, but curiously, they start out younger than other breeds, as their first year of life is equivalent to 12 human years. At 2 years old, they will be 22 human years, but by the time they reach 3 dog years, they will be about 31 human years. By 6 dog years, a large breed will be about 49 human years.
What is the science behind the difference between dog age and human age?
The science of canine aging and how dog age correlates with human age is still unclear, as aging differs from dog to dog and the field is far from perfect. That said, canine gerontology is definitely a growing field, and many researchers are making progress toward understanding how dogs age and how to extend their lifespan.
Relatively Recent Research A 2019 study devised a more accurate way to determine a dog’s age by comparing changes in dog and human DNA over time, but the study only looked at Labrador retrievers, so it’s not yet clear whether this formula for determining age applies to all dog breeds.
Dog life stages
Dogs have three main life stages: puppyhood, adulthood, and seniorhood.
Puppies: 0-2 years old
This stage varies in age range from dog to dog, as some breeds take longer to mature than others, but generally speaking, puppyhood refers to the first 1-2 years of a puppy’s life. This is the most important stage for a dog, as this is when they are socialized, trained, and learn about the world around them.
Adults: 2 to 8 years old
Once your dog has reached its maximum weight and height, it officially becomes an adult. Keeping your pet healthy during this adult period is essential to its longevity, so be sure to keep it up to date with vet checks and vaccinations.
Seniors: 8 years and older
As your dog reaches senior years, he or she becomes more susceptible to illnesses and you will need to closely monitor their health.
Dog lifespan by breed size
| size: | Life expectancy: |
| Small dogs (under 20 pounds): | 10-15 years old |
| Medium dogs (21-50 lbs): | 10-13 years old |
| Large Dogs (51-100 lbs): | 8 to 12 years old |
| Large breeds (over 100 lbs): | 8 to 10 years old |
sauce: American Kennel Club
Main factors that influence the ageing process in dogs
While genetic factors such as a dog’s size play the biggest role in how quickly they age, other factors can also influence this.
What your dog eats and how much he eats also affects how he ages. Just like us humans, dogs who eat unhealthy foods that are high in calories instead of the nutrients they need, or who overeat, can develop obesity and other health problems, which can accelerate aging. The best diet for your dog is a nutritionally sound, high-quality dog food that meets all of your dog’s nutritional needs.
Environmental factors such as an unhealthy home environment or an environment that doesn’t meet all of your dog’s needs can also cause your puppy to age prematurely.
But overall, genetics and size are the most important factors in how your dog ages.
Conclusion
While the saying “seven human years equal one dog year” may not be true, you can still determine your puppy’s approximate age. How dogs age is still a mystery, but we’re learning more about it. We do know that different sizes of dogs age differently. For example, a small dog that is 6 years old in dog years is about 40 years old in human years, and a medium dog is 42 years old in human years. Meanwhile, a large dog puppy is about 45 years old in human years, and a giant dog is about 49 years old in human years.
Featured image credits: ressmaster, Shutterstock
