Space per bird is the whole calculation
Coop size is the number of birds times a per-bird allowance, split between the enclosed coop and the outdoor run. Crowding drives stress, disease and pecking, and it drops egg output, so the run allowance is generous on purpose.
Allowance by breed size
| Breed size | Coop (indoor) | Run (outdoor) | Example |
|---|---|---|---|
| Small (bantam) | 2.5 ft² | 4 ft² | Silkie |
| Standard | 3.5 ft² | 8 ft² | Rhode Island Red |
| Large (heavy) | 4.5 ft² | 10 ft² | Brahma |
Mixing sizes? Average the allowances. Five bantams plus five standards works out to about 3.0 ft² coop per bird. Cold climates want roughly 20 percent more coop floor for insulation room.
Everything else scales with the flock too
- Nesting boxes. One per three to four hens; hens share, so don't build one each.
- Roost length. About 8 inches of perch per bird, set 2 to 3 feet off the floor.
- Ventilation. Roughly 0.4 ft² of vent per square foot of floor in temperate climates, up to 1.0–1.5 in the tropics — it matters more than lighting.
- Run over coop. The outdoor run is the bigger number. When space is tight, protect the run allowance first.
Common questions
How much coop space does each chicken need?
About 3 to 4 square feet of indoor coop floor for a standard-size bird, plus 8 to 10 square feet of outdoor run. Bantams need less (roughly 2.5 indoor, 4 outdoor); heavy breeds need more.
How big a coop for 5 chickens?
For five standard hens, plan around 17 to 20 square feet inside and 40 to 50 square feet of run. A 4x5 coop attached to a 4x10 run works well.
How many nesting boxes do I need?
One box for every three or four hens. Hens share boxes, so you do not need one each. For a dozen birds, four boxes is plenty.
