About how many chickens can I expect to fit in a coop 8'x12' with roosts and nest boxes ? Its 6 ft tall. I have 10 chickens ages 5 months - 1 yr of age in another coop. I have (9) 3 month old chicks that will need the new 8x12 coop, and I have 2 hens sitting on babies about to be hatched about 22 babies total. This 8 x 12 coop is being made for the teenager chicks. So they will have a safe place to sleep at night. This is only for sleeping and then as they get older it will give them a place to lay their eggs. I have a pen that can be converted into a run if I move it over to the new building.