Here's what the 4 sq ft rule means in practical terms. Newbies take note.
Get 16 floor tiles and lay them out, 4 to a side, in a square. That is 4 sq ft. Now put a 5 gal bucket in that area. That represents a full grown hen.
Or just go in the kitchen or other area and mark this off.
What you are seeing is the total indoor living space you are affording an active creature with a high metabolic rate, one who poops everywhere constantly. 70% of what goes in a chicken comes back out the rear.
If the coop is only for roosting and laying and you boot them out after sunrise as you should, then okay, that'll do. Youll still be busy cleaning up after them, but it'll do. Offer less at your peril (and theirs).
Outside? 10 sq ft is hardly enough. Sorry to you formulaic types, but, well - there it is. Whatever you think you have available outside, triple it and then add 25% more as saftey margin. And then look for more.
MP said this:
It is better to have too much space than to cram them in. Over crowding causes pick, pecking and all sorts of troubles.
The "all sorts of trouble" part is a vague way of saying
"the various maladies and health risks which are filth borne" (read the word "filth" as shi*T)
Wanna see what chickens should have in the backyard environment? Go here:
https://www.backyardchickens.com/forum/viewtopic.php?id=69133
While youre looking at this, get a good look at his attached run. I make it to be about 10x10 or 100 square feet; that's 2.5X the recommended allowance. He has only 4 birds in there - take a close look at the condition of the ground inside that run.