Without knowing more about his parents it is difficult to guess what the "proper" size would be. If his parents were small for their breeds he could be significantly smaller than a purebred Dane. It is also possible that he had one parent who was mixed Dane/Aussie and the other could be unknown (sire). If that is the case he could end up any size. Based on how you describe him it seems like he is running a little small. My male Great Dane (purebred) was 25 lbs and up to my husband's knee at 11 weeks. My husband is 6'2".
Answered by tmarie68 - 12/12/2013 5:38:52 PM