How the calculator works
Every extension poultry guide uses the same square-foot-per-bird rules. The numbers below are the ones that keep hens from pecking each other, keep the coop dry, and keep eggs in the boxes instead of on the floor.
Eight standard hens need a 32-square-foot coop (a 4 by 8 sheet of plywood is the floor, which is why so many coops are that size), an 80-square-foot run, 6 feet of roost and 2 nest boxes. Lock them inside through a northern winter and the coop should grow by half; let them free-range daily and you can shave a quarter off.
Space per bird
| Bird | Coop floor | Run | Roost | Hens per nest box |
|---|---|---|---|---|
| Bantam | 2 sq ft | 5 sq ft | 6 in | 5 |
| Standard layer | 3–4 sq ft | 8–10 sq ft | 8–10 in | 4 |
| Large / dual-purpose | 4–5 sq ft | 10–12 sq ft | 12 in | 3 |
| Meat birds (Cornish Cross) | 2 sq ft in tractor | n/a | none | none |
| Ducks | 4–6 sq ft | 15 sq ft + water | none, floor nests | 3 |
Why crowding costs you eggs
Under about 3 square feet per bird, flocks start feather-pecking, egg-eating and bullying the lowest hen off the feeder. Ammonia builds faster than bedding can absorb it, and damp litter is where coccidiosis and respiratory trouble start. Hens that are stressed lay less, so a cheap coop that is too small is the most expensive coop you can build.
Ventilation without drafts
A coop needs about one square foot of permanent opening per ten square feet of floor, placed high, above roost height, so moist air leaves without wind blowing across the birds. Hardware cloth over the openings, never chicken wire; raccoons go straight through chicken wire. In the South, add a second set of openings you can close in January and open in June.
Roosts and nests
A 2 by 4 laid flat (wide side up) is the roost most backyard keepers settle on: hens can sit on their feet in the cold. Set it 18 to 24 inches off the floor, higher than the nest boxes, or they'll sleep in the boxes and foul the eggs. Nest boxes are 12 by 12 by 12 inches for standard breeds, 14 inches for the big ones, with a lip to hold bedding in and a slanted top so nobody roosts on it.
Frequently asked
How big should a coop be for 6 chickens?
24 square feet of floor (4 by 6), a 60-square-foot run, 4.5 feet of roost and 2 nest boxes. A 4 by 8 coop gives you room for two more, which you will want.
How many chickens fit in a 4x8 coop?
Eight standard hens comfortably, ten if they free-range daily, six if they'll be locked in through winter. Twelve bantams.
How much run space per chicken?
10 square feet each for standard breeds, 8 if they get out to forage regularly. Less than that and the run turns to bare mud and manure within a month.
How many nest boxes for 10 chickens?
Three. One box per four hens is plenty; they'll all want the same one anyway.
Do chickens need a run if they free-range?
Yes, for the days you can't let them out and for the first week in a new place. Size it at 8 square feet per bird instead of 10.