Did you know that the standard calculation – one dog year equals seven human years – is not really accurate? In fact a one year old dog is more equivalent to a 15 year old human and a two year old dog equals 24 human years. Size is also a factor in dog aging.  At five years old most dogs are equivalent to a 36 year old human but after that the gap between a small dog and a large dog starts to widen.

• For a small dog – under 20 lbs. – add 4 human years for every one dog year after age five
• For a medium dog – between 20 and 50 lbs. – add 5 human years for every one dog year after age five
• For a large dog – over 50 lbs. – add 6 human years for every one dog year after age five

Using this formula, by the age of 13, a small dog is equivalent to a 68 year old human while a large dog is comparable to an 82 year old human.