How Big a Coop Do 21 Chickens Need?
21 standard-size chickens need a 84 sq ft coop, a 210 sq ft run, 210 inches of roost, and 6 nesting boxes.
| Bird type | Coop | Run | Roost | Nest boxes |
|---|---|---|---|---|
| Standard breeds | 84 sq ft | 210 sq ft | 210 in | 6 |
| Bantams | 42 sq ft | 168 sq ft | 168 in | 6 |
| Heavy breeds | 105 sq ft | 210 sq ft | 252 in | 6 |
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 21 standard chickens, a 6 × 14 ft coop covers the84 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 210 sq ft run works out to roughly a21 × 10 ft enclosure attached to the coop.
Inside, plan 210 inches of roost — 5 four-foot roost bars mounted higher than the nest boxes — and 6 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.