How old would a chihuahua be in doggie years if they are 2 years old?

There isn't a simple answer. Age progression depends on several factors, including breed (or mix) and size. Small dogs mature faster than large dogs and, as a rule, live longer. A chihuahua will usually be full grown by the time he is a year old where a German shepherd may need three years to full maturity.

The maturation rate is faster in the earlier years and slows down after the dog is fully grown.