The common phrase would lead you to believe that one dog year roughly equates to seven human years, but this is certainly not representative. It is purely down to maths.
The global life expectancy for a human is a little over 67 years while a dog is a little under 13 years, meaning that the true average would be about five years, not seven. Also, smaller dogs tend to live a lot longer. In addition, dogs tend to be fully developed by their first birthday whereas humans are not, so a dogÂ’s first year is really more like 20 in human years!