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.

Figures reviewed against university extension guidance · Last reviewed July 2026

Bird typeCoopRunRoostNest boxes
Standard breeds84 sq ft210 sq ft210 in6
Bantams42 sq ft168 sq ft168 in6
Heavy breeds126 sq ft210 sq ft252 in6

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.

Other flock sizes

Sources