Thursday, August 18, 2011

❏This vs That ❐: Dog Years vs Human Years

Welcome to Thursday's

It's common knowledge that dogs age faster than people but there is a popular belief and conventional wisdom which states that one dog year equals seven human years.  So a two year old dog corresponds to a fourteen year old human teenager in the terms of this aging processes.
This oversimplified calculation, however, is completley incorrect and inaccurate.  That's kind of like saying a one year old dog can give birth and so can a 7-year old child!   In fact, determining the exact age of a particular dog, relative to a human scale, is much more complex than that with the ratio of dog years to human years varying with the weight, breed, and health condition of the dog.    The ratio is higher during first years of the dog’s life and decreases as the dog ages.   In fact, dogs reach adulthood within the first couple of years meaning they have a very short "childhood" and a very long middle-age.  
Hence, dogs mature more quickly than children in the first couple of years. As it turns out, for many breeds, the human equivalent of a one-year-old dog, or the first year of a dog's life is between 10 and 15 years - not seven. 

Later, depending on the dog's size in pounds typical for its breed, the same number of actual years corresponds to different number of human years, with this scale varying greatly from breed to breed.

Chart Example:

There are four main groups of dogs each having a different ratio of translating dog years to human years: small dogs (20 pounds or less), medium dogs (21-50 pounds), large dogs (51-90 pounds) and giant breeds (more than 90 pounds). 
Large dogs mature more slowly but at the age of five they will be considered elderly, while small and toy breeds are not considered seniors until the age of ten.
There is actually a simplified generic formula used by many canine experts for determining dog age: 10.5 dog years per human year for the first 2 years, then 4 dog years per human year for each year after.

Online Conversion - Dog Years Calculator

Breed specific calculator:

Pedigree Dog Age Calculator

No one formula for dog-to-human age conversion is scientifically agreed on, although within fairly close limits they show great similarities.

So overall, when a dog reaches the age of two, he is roughly, (give or take a year), 24 in human years - not 14 as commonly believed.
After that, add four years to every year after age two.  For example, a three-year-old dog is equivalent to 28 in human years; a four-year-old is 32, a five-year-old, 36, a six-year-old, 40--and so on.
Of course, you must take the dog's size into consideration, since smaller dogs generally have longer life spans than larger dogs, with toy breeds tending to live the longest and giant breeds, the shortest.
For example, according to the above method, a six-year-old dog is considered 40 in human years, when in fact a larger dog may actually be closer to 42. However, veterinarians consider this a good general chart to follow for all dogs. 

Resource(s):,, wikipedia,

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