A dog owner will often compare the age of a dog with that of a human. This correlation can be complex.


Factors impacting the correlation between the age of a dog and a human:

(1) breed of the dog (and race of the human)

(2) weight of the dog

(3) lifespan of humans and the dog breed

(4) milestones in development (sexual maturity, etc)


Using 1 dog year as equivalent to 7 human years is inaccurate.


A dog at 2 years of age is approximately equivalent to a human adult of 22-24 years. After 2 years of age the correlation between the dog and human age is roughly linear but breed dependent. Before 2 years the relationship is exponential; a dog 1 year of age is equivalent to an early adolescent.


Using simple proportions:


human age equivalent in years =

= (dog age in years) / (expected lifespan for the dog in years) * (human life expectancy)


Using the date at for dogs from 2 to 18 years:


human age in years =

= (4 * (dog age in years)) + 16


After 18 years the dog is older than dirt.


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