German shepherd weight and height

Question
I have a German Shepherd pup who is currently coming up to 7 months old and wondered if there is anyway to roughly calculate what height and weight he will end up being. He is very lean, weight at the moment is around 36kgs and I have been told that he is a big pup so cant use the conventional growth charts. I feed him on a mainly dry mix of Purina which has a good protein content.

Answer
My experience is that they really level off at that age and don't get a lot bigger.  However, bigger dogs tend to be bigger because they continued growing longer.  Check the ends of his leg bones.  If they are still knobbier than an adult's, the growth plates are still open and he has more growth to come.  

Being lean is good.  With Shepherds, it is better to leave the ribs show a little than to temp them to eat more by adding rich food ruining the careful balance dog chow provides.  For the same reason, it is better to make an early switch to adult chow, slowing growth and allowing the joints more time to develop.