Dog Years Calculator

Ever wondered, if your Dog was a human, How old would he/she be? Every dog breed is different, Use our Dog Age Calculator to figure out the age of your dog in Human Years.

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Up until recently we thought we had it figured out. We knew how to count human years, how to count dog years and how to convert them. If asked to translate a dog’s age in human years we would do it by multiplying by seven. After all, conventional wisdom states that one canine year equals seven dog years. However, in this article we will explain that this particular conventional wisdom is not correct.

As any other conversion, converting dog years to human years requires math. And math is never simple. Therefore, understanding your dog’s exact age is not as easy as multiplying its human years by seven. This is mainly because the actual age is influenced by several variables that cannot be compiled in a mathematical equation.

The 7-years rule suggests that humans age seven times slower than dogs. If this was true, our lives would be much different – we would be able to reproduce when 7 years old and live for as much as 150 years. Obviously this is not how things work and obviously the 7-years rule is not accurate. The truth is, dogs reach full sexual maturity only one year after birth. It should be noted that this statement is quite generalized. Larger dog breeds tend to mature slower than smaller breeds. However, one year is considered to be the average age. In comparison, it takes humans more than 10 years to reach full sexual maturity.

Why convert dog years to human years?

People have always loved to anthropomorphize dogs. Giving dogs human age is a suitable example. However, giving dogs human age is not just a whim. Knowing your dog’s age in human years helps you determine its life stage. Once the dog’s life stage is determined it is easier to understand its needs and provide life-stage specific care.

In the canine world, there are six life stages:

  1. Puppy (birth to 6-7 months of age) – at this point dogs go through major physical mental changes. During this phase it is important to focus on socialization, training, nutrition and handling.
  2. Junior (until 1-2 years of age) – at this point dogs are sexually mature but still physically growing. This stage is usually marked by certain behavioral issues like short attention span, fear and wandering.
  3. Adult (from 1-2 years of age to middle age) – at this point dogs are socially mature and finished growing physically. However, they need proper attention regarding behavior, physical activity, nutrition and medical needs.
  4. Mature (from middle age to three-quarters of the entire lifespan) – at this point dogs do not have specific needs but do require annual vet exams.
  5. Senior (the last quarter of the dog’s expected lifespan) – at this point dogs eat less, sleep more and are reluctant to physical activity.
  6. Geriatric (at life expectancy and beyond) – at this point dogs need bi-yearly vet examinations because their physical health can quickly decline. When parenting a geriatric dog, it is important to recognize if your dog is suffering.

Sadly, the aging process develops sneakily and differently with every dog. Male and female dogs of the same breed have similar life expectancies. On average spayed and neutered dogs live one year longer than non-spayed and no-neutered dogs of the same breed. Ultimately, mutts tend to live longer than purebreds of the similar size and weight.

The objective indicators that a dog is old include:

  • Gray snout
  • Reluctance to move
  • Decreased performance ability
  • Increased need to sleep and rest
  • Bleary eyes
  • Dental pain and tooth loss
  • Bloating and constipation
  • Coughing
  • High blood pressure
  • Character changes

Documented in the Guinness Book of World Records, the oldest dog in the world had 29 years and 7 months. It was a terrier-dachshunds-beagle mix and weighed only 13 pounds. Another interesting fact is that 83% of the oldest confirmed dogs in history were less than 20 pounds.

Fortunately, nowadays, dogs live much longer lives than their canine ancestors. In 1900 less than 20% of the dogs lived past the age of 6. In 2010, that percentage was 44%.

How do researchers come up to calculate dog years?

People have been comparing human to dog life spans for centuries. The origins of those comparisons are obscure and scarce. However, evidence show that people were trying to calculate their dogs’ ages since the 1200s. An inscription on the Cosmati Pavement in Westminster Abbey, dating back to 1268, states that one human year is equivalent to nine dog years. Later on, in the 1950s, dogs had two years trimmed off their lifespan and the 7-year rule became popular. This 7:1 ratio was based on pure logic and statistics. At that time, on average, humans lived to about 70 years while dogs lived to about 10 years. In 1953, based on the research conducted by A. Lebeau, it was established that:

  • During their first year of life, dogs age 15-20 times faster than humans
  • As dogs age, the ration gradually slows down to 1:5.

Now we know that dog years and human years do not have a linear relationship. In fact, dog years go way faster than human years. Simply put, humans and dogs age, grow and develop at different rates. When compared to humans, dogs age faster during the first two years of their lives and then the aging tendency slows down. For example, according to Lebeau, a 1-year-old dog equals a 15-year-old teenager but a 2-year-old dog equals a human that is old enough to legally drink.

To be more accurate:

  • A 1-year-old dog equals a 10-15 years old human. Both are sexually mature and physically grown but still a bit lanky.
  • A dog’s second year of life equals 3-8 human years. This is in terms of mental and physical maturity.
  • After the first two years of life, the ratio is 5:1 for small and medium breeds; 6:1 for large breeds and 7:1 for giant breeds. To illustrate this, a 10-year-old Great Dane would be 70 dog years old, a 10-year-old Cocker Spaniel would be 60 dog years old and a 10-year-old Pug would be only 50 dog years old.

Why do smaller dogs live longer than larger dogs?

Generally speaking, in the animal kingdom, large mammals like elephants and rhinos, live longer than small mammals, like mice and guinea pigs. However, when speaking about dogs, this is not true. It is well-established that smaller dogs live longer than large dogs. For many years, this peculiar phenomenon has baffled scientists. The relationship between body mass and life expectancy is quite complex and not fully understood. Nevertheless, recent studies suggest that a dog’s life expectation is reduced by 1 month for every 2 kilograms of body mass. The reason why is not known but there are several evidence based and objective options:

  • Larger dogs tend to succumb to age-related illnesses sooner than smaller dogs
  • Due to their accelerated growth, larger dogs are at higher risk of abnormal cell growth and consequently cancerous changes.

Great Danes grow quickly in size but do not reach maturity until 2 years old. Their average lifespan is 6-8 years. On the flip side Yorkshire Terriers reach maturity when less than 12 months old and have a particularly long lifespan that often exceeds 15 years. Therefore, both the lifespan and the aging rate depend on the breed.

A 4-year old Miniature Schnauzer is younger than a 4-year-old Neapolitan Mastiff. However, since smaller breeds mature more quickly, it is only logical to assume that a 1-year-old Chihuahua is more mature than a 1-year-old Great Dane.

Dogs are considered old when they reach three-quarters of their life expectancy. In general, dogs enter their senior years when 7 years old. More precisely:

  • Large dog breeds are considered seniors after the age of 6
  • Medium dog breeds and mutts are considered seniors after the age of 7
  • Small dog breeds are considered seniors after the age of 9.

It should be noted that a dog’s life expectancy is not determined exclusively by its breed, weight and size. This variable is affected by the following factors as well:

  • Lifestyle
  • Nutrition
  • Type and extent of physical activity
  • Genetic factors
  • Physiological state (neutered, spayed or intact)
  • Place of residence (indoors, outdoors, wild).

Last but not least, it is worth mentioning that chronological, biological and emotional aging are completely different processes.

Conclusion

In a nutshell, the first year of a dog’s life equals 15 human years. After that, the dog’s ageing pace is determined by its size and breed. This is mainly due to selective breeding. Dogs come in a huge variety of breeds and sizes. Therefore, their ageing paces and life spans significantly differ within the specie.

So…all in all, the seven-year myth is not true and it has not been true for a relatively long time now, However, even today most dog owners default to this traditional rule, use our Dog age calculator to get the correct results. As the curator of the Charles R. Connor Museum at the Washington State University, Kelly M. Cassidy, who studied longevity in dogs said: ,,You can’t really kill the seven-year rule’’. And maybe it should not be killed. From a health standpoint, the rule can be used to illustrate how fast a dog ages compared to a human. Therefore, the rule although not accurate, is quite convenient.

With more and more dog parents looking to both extent their dog’s lifespan and improve their quality of life, as a science field, the canine gerontology’s popularity is on the rise. Consequently, we can hope that newer and even more accurate data will soon be available. As for now, translating a dog’s age in human years remains a rather challenging task.