How Big a Coop Do 18 Chickens Need?
18 standard-size chickens need a 72 sq ft coop, a 180 sq ft run, 180 inches of roost, and 5 nesting boxes.
Figures reviewed against university extension guidance · Last reviewed July 2026
| Bird type | Coop | Run | Roost | Nest boxes |
|---|---|---|---|---|
| Standard breeds | 72 sq ft | 180 sq ft | 180 in | 5 |
| Bantams | 36 sq ft | 144 sq ft | 144 in | 5 |
| Heavy breeds | 108 sq ft | 180 sq ft | 216 in | 5 |
Rates: 4 sq ft coop and 10 sq ft run per standard bird (Virginia Cooperative Extension; Colorado State University Extension). Run figures assume birds are confined; free-range flocks need only the coop numbers.
What that looks like in practice
For 18 standard chickens, a 6 × 12 ft coop covers the72 sq ft floor requirement. Floor space means usable floor — don't count feeder footprints or the area under nest boxes mounted lower than 18 inches. The 180 sq ft run works out to roughly a18 × 10 ft enclosure attached to the coop.
Inside, plan 180 inches of roost — 4 four-foot roost bars mounted higher than the nest boxes — and 5 twelve-inch nesting boxes in the darkest corner. These are extension-guidance minimums for healthy birds, not luxury targets: cold climates, bossy roosters, and pecking-prone breeds all appreciate more room.
Keeping different birds, or planning to free-range? Use the full Coop Size Calculator to adjust for bantams, heavy breeds, and run type.
Other flock sizes
Sources
- Virginia Cooperative Extension — Small-Scale Poultry Housing (pub. 2902-1092)
- Colorado State University Extension — Brooding and Space Requirements for Poultry (2.502)