I'm new to chickens, so before deciding on my coop, I spoke to a lot of local chikcen farmers. The people who keep lots of chickens and sell their eggs usually say 1 to 2 square feet per chicken of indoor space (usually 1), and they don't even build runs, they just let them free range and if a predator gets one, so be it, they replace it. The people who keep chickens as pets/layers recommended 2 to 3 square feet per chicken.
Then I came here and saw the 4 square feet per bird thing and I thought...whoah, what gives? I have 15 chickens, 11 big ones and 4 bantams. Of the 11, one is a rooster, of the 4, I don't know, because they are teeny. Following local wisdom I built what I thought was a palatial coop, 8x4 with 6' ceiling and 8' of nest boxes bumping out another 14" (haven't partioned them yet so I'm not sure how many I'll make. I'm also building a 15'x15' run, not including the area under the coop which is also accessible and protected.
If I followed the formula recommended here, I would need an 8x7 coop, another 3'x4'. That doesn't sound unreasonable. I could also add a second floor/loft to my coop that will give me more room than that. The thing is, the local chicken keepers think I'm crazy when I bring up 4 square feet per bird. They say "What the hell does a chicken need with 4 square feet?"
One of them, who is internet savy, said something interesting: "The idea that a chicken needs four square feet of coop space is built on a semantic mistake. When those numbers were firsted introduced, people were talking about the henhouse and run as being the 'coop.' Now the hen house is the coop, and people think that needs to be 4 square feet per bird. A large henhouse can actually be bad for the health of the birds because chickens heat their coops with body heat, and a tight space is more easily heated. A hen house that is too large will be too cold in some climates."
What are your thoughts on this?