It really varies widely on people own personal feelings, experience and what they have read. My own personal feeling is 4sq ft per bird of coop space. The bigger the outdoor run the better is my feeling just because i want my birds to feel as free as possible while having the safety of an enclosed run. If you live in a cold climate as I do, think of the living conditions of your bird in the winter time when they are more than likely going to be staying exclusively in the coop when its too cold to go outdoors. How much space are they going to have to move around in the coop. So if your coop is 4x8 that is 32 square feet of coop space. So I would say IMO, 8-10 birds max. But do what works for you, as long as they aren't fighting and the flock is healthy than do what works! Hope this helps.