How old is your dog?

It depends on size, smaller dogs are 6 while larger are 7

Seven is actually an average, it depends on dog size, breed, and their human age (when they're younger they develop faster, and the older they get, the less dog years a human year is worth)

You can, however, make a graph for around about the average that, while not perfect, is still better than the 'seven dog years' yardstick. I'm not denying that a chihuahua and a great dane would age rather differently, but this is a good chart from which to make a semi-informed guesstimate.