I am just finishing my coop. 1.2mx1m plus 2 laying boxes, It's in a run area 2.4x1.5m roughly and I plan to free range them in the yard over the day. I have 7 eggs in the incubator so will have seven in there until I can identify the roos. A bit crowded to start with from my reading, I have never had chickens before so hope I'm doing OK.
You might follow the link in my signature to get some of my thoughts on size. I don’t believe in magic numbers but instead give you things to consider. We are each so unique that one magic number cannot fit us all.
My facilities consist on an 8’ x 12’ walk-in main coop, a 12’ x 32’ run, plus an area roughly 45’ x 90’ inside electric netting. In addition I have a 4’ x 8’ elevated grow-out coop. An 8’ x 12’ section of the main run can be isolated with this grow-out coop. Inside that electric netting I have another 4’ x 8’ coop on the ground. When the main coop is really crowded I sometimes keep a broody hen and her chicks out there at night just to reduce the numbers in the main coop.
My normal laying/breeding flock consists of one rooster and between 6 and 8 hens. At times my total number gets to over 40 chickens of various ages, many fairly young. When they get to butcher age the cockerels go into the freezer but I usually keep the pullets around a while so I can evaluate them as replacements. Last summer I had 7 hens and 14 pullets all laying at the same time.
Right now I have 6 hens and one rooster in the main coop. With them are 7 cockerels and 2 pullets, 20 weeks old. I’m waiting for a decent weather day to put those cockerels in the freezer. I also have 11 ten-week-old chicks sleeping in the grow-out coop but roaming with the main flock during the day. Once those cockerels are gone I’ll move them to the main coop.
I have 3 coops that are 10x10 with a 10x20 run attached to each.
Coop 1 I have my 8 laying hens. They are coming 2 yr olds and consist of 2 Buff Orps, 3 Black Aussies and 3 EEs. I did have an English Orp cockerel in with them, but he went to freezer camp this past weekend.
Coop 2 I have my 11 Cream Legbars. They are 3 to 3 1/2 months old.I have 2 cockerels and will be moving them into coop 1 in the next couple of months.
Coop 3 I have 3 Splash English Orps. I sold 2 Blues and put my other Splash cockerel in freezer camp. I have these 3 up for sale, so when this pen opens, I will be able to split up my Legbar pen.
I really try to keep 10 or less chickens per coop. They could hold more, but I find this number works well for me. They all like to hang out in the coop, so I want plenty of room for them.
I do not free range. I still have one pasture fence to put up and I have 2 dogs that were not raised around chickens. I know one or both would get a chicken if it was out running around, so I keep them all up.
Don't think free ranging can allow you to skimp on coop size or not building a secure run.
Predators events can have you wanting/needing to keep your birds confined for days/weeks/or long term.
Climate also has a bearing on coop size and run design.
My coop is 6' wide x 16' long for winter...length can be split to 12' and 4' for growing out chicks in spring/summer.
Main run is 8' x 50' in 'L' shape, partition run(for coop split) is 8' x 12'....almost all mesh roofing, very little weather protection.
Keep 15 birds over winter and have had up to 30 in spring/summer with chicks growing out.
15 is fine for winter with limited outside time due to snow depth and brutal temps, 30 got crowded even in summer.