Child Support is calculated using a myriad of factors. It is strongly recommended that you see a lawyer about the factors needed to be used in determining the child support in each and every case. Here is the link for the Georgia Court calculator:
http://www.georgiacourts.org/csc/
Again, remember that the facts that are put into the calculator determine the proper amount or proposed amount of support but it is ultimately in part a decision made by and at the discretion of the Court.