How big of a pen do I need for 20 Meat Chickens?
They need to be able to get away from each other and should have something to hide in or behind. If you try to fit 20 birds into 40 sq. ft. you'll go through a lot of bedding. I mean a lot.
In the brooder they have 7-10 sq. in. under the brooder itself plus a fair amount of space to run, eat and drink away from the brooder. Once on pasture, we go for 2 sq. ft. on tractors that are moved to fresh grass daily.