Is it 10 or 20% of the ARV of what can go on the land?

I am also having a hard time finding dimensions for a plot I'm on the verge of purchasing in Henry County. New ordinances (so i have heard from a developer) say that all new builds must be 150ft of road front and no flag lots. I have a good size lot, but I'm wondering how many properties I can fit on it, in order to make an educated guess on offer.