I think the smaller dogs take less time to be full grown. The bigger ones....like 2-3 yrs. My Chihuahua was pretty much full grown at about 6 months, maybe just a tad more filling out. My Dobeman was about as tall as he'd get at about 10 months or a year, but has been filling out ever since. He's 2 now and he will probably continue muscling up a little more over the next 1/2 yr. or even a little longer. They vary a little bit.