I always wondered how to calculate a dog's age after watching Animal Prescient on the Animal Channel. On the show, a woman though she had an old dog. The agent told the women that the dog was not old and that one dog year equals seven human years was a myth. I just decided to research this for myself and find out that the first two dog years equals 10.5. Then add four dog years for each year following the dog's second birthday. A three year old dog is 25 years old (10.5+10.5=21and 21+4=25). I just found a website that will calculate your dog's age for you and it is
Online Conversion - Dog Years Calculator. This calculation of a dog's age is not an exact science, because large and small dogs age differently. Wikipedia shows a chart that shows a difference in how dogs' age based on size (
Aging in dogs - Wikipedia, the free encyclopedia). I am glad you asked this question. I always wanted to research this for myself.