I've read that you need at least 7 sq foot per bird. also will this run be portable? I think you can get away with a little less space if you're moving them to fresh ground every day or two.
we have 12 2-month old chicks in an 8 x 8 pen and I have to say that I can't imagine 12 full size chickens in there happily. I'm trying to figure out how I'm goign to expand it. This is a portable pen by the way, that I move daily.
I also plan to let them roam about the yard when we're home and outside, but for safety's sake, I need the portable pen.