An 8-foot by 10-foot coop gives you 80 square feet of indoor floor. With daily run access and a temperate climate, that fits 18 to 20 standard-size laying hens or 13 to 15 heavy breeds. The 8×10 is where walk-in coop design hits its sweet spot — large enough to house a meaningful flock plus integrated storage, small enough to fit most suburban side yards.
The math behind 80 square feet
At HatchMath's 4-sqft working figure, an 8×10 (80 sq ft) holds 20 standard hens. At the published with-run-access range:
- 3 sq ft / bird: 26 hens (tight, edge of comfort)
- 4 sq ft / bird (HatchMath default): 20 hens
- 5 sq ft / bird: 16 hens (comfortable)
- Heavy breeds at 5–6 sq ft: 13–15 birds
- Full confinement at 8–10 sq ft: 8–10 hens
Walk-in layout: what fits at 8×10
80 sq ft of floor accommodates a full walk-in layout comfortably. Standard configuration:
- 5 nest boxes (1 per 4 hens) cantilevered off one long wall, accessed externally for egg collection
- 20 feet of roost (long-wall + a perpendicular short rail) for 20 hens at 12 inches per bird
- Feed station with vertical-sided feeder and stored 50-lb feed bag in a metal trash can
- Watering station with heated base for winter use
- Storage corner (~10 sq ft) for bedding, tools, supplemental oyster shell, grit
- Optional brooder pen in one corner (~12 sq ft) for raising chicks alongside the adult flock
Run space for an 8×10 coop
For 20 hens at 8–12 sq ft per bird, the run wants 160–240 sq ft — a 12×20 or 16×16 fenced enclosure. Hot/humid climates push to 200–280 sq ft. Total footprint (coop + run) for a 20-hen 8×10 setup runs 240–340 sq ft — a meaningful yard commitment. At this scale, many keepers add a small quarantine pen attached to the run for sick or new birds (~12–16 sq ft).
Ventilation for an 8×10 walk-in
The 8×10 walk-in needs 7.2–8.8 sq ft of vent area in a temperate climate per the ventilation calculator. At walk-in ceiling height (7+ feet), bump that 15–20% to account for the larger air volume — call it 8.5–10.5 sq ft total. A continuous ridge vent (~10 ft × ~1 sq ft) plus two 18×24-inch gable louvers handles most of the high-vent budget; two floor-line cutouts on opposite walls cover the low intake.
Frequently asked
How many chickens can I keep in an 8×10 coop?
18–20 standard-size laying hens with daily run access in a temperate climate. The 8×10 footprint gives 80 sq ft of indoor floor; at 4 sq ft per bird, that's 20 hens at the upper bound. Heavy breeds (Brahma, Jersey Giant, Cochin) drop to 13–15 birds. Full confinement (no run) limits the 8×10 to 8–10 hens. The 8×10 is the most-popular walk-in size for serious backyard flocks of 15+ birds.
Is an 8×10 coop too big for a backyard?
Depends on the flock size and yard. For a 15–20 bird flock with proper run space (160–280 sq ft additional), the total footprint runs 240–360 sq ft — meaningful but achievable in most suburban side yards. For flocks under 12 birds, an 8×10 is over-built; you're paying for material and yard commitment you don't need. The 8×10 starts to make sense at 15+ birds or when a walk-in design with feed/bedding storage is the priority.
How much run space does an 8×10 coop need?
8–12 sq ft per bird outdoors. For 20 hens that's 160–240 sq ft of run — roughly a 16×16 or 12×20 fenced enclosure. For 18 hens, 144–216 sq ft. Hot or humid climates push to 200–280 sq ft. Plan run + coop together; total footprint (coop + run) for a 20-hen 8×10 setup runs 240–340 sq ft, which is a noticeable yard commitment. Many keepers at this scale also include a small isolation/brooder pen attached to the run.
Does an 8×10 walk-in coop need a different ventilation calculation?
Slightly more vent area than the calculator's standard output suggests. The calculator's 1:10 vent-to-floor ratio is per-floor-area, not per-volume. Walk-in coops have higher ceilings (7+ feet vs 4–5 feet for chicken-only coops), which means more total air volume per unit of floor — vent throughput should scale slightly higher to account for it. A practical adjustment: bump the calculator output by 15–20% for walk-in builds. The high outlets (ridge vent, gable louvers) handle most of this; low intakes scale linearly with floor.
Related
- Coop size + run space calculator →
- How many fit in an 8×8 coop →
- How many fit in a 6×8 coop →
- Coop ventilation for 20 chickens →
- Coop ventilation calculator →
By Jimmy L Wu. Indoor floor space anchored on OSU Extension EC-1644, UMN Extension, Penn State Extension, and University of Maryland Extension. The 4-sqft working figure, run-space range, and walk-in vent adjustment are HatchMath methodology. Engine logic in lib/poultry/coopSize.ts. Not veterinary advice.