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How Coop Space Requirements Are Calculated
This calculator uses the most widely cited minimum space standards from university extension programs and the National Chicken Council, combined with practical adjustments for climate and confinement style.
Minimum Indoor Coop Space
The standard minimum is 4 square feet per standard hen inside the coop — the sleeping, roosting, and nesting area. This is a genuine minimum; more is always better. Cold climates require larger indoor space because hens spend more time inside during winter. Bantam breeds need only 2–3 sq ft; heavy breeds need 5–6 sq ft.
Minimum Outdoor Run Space
The standard minimum is 10 square feet per standard hen in an enclosed run. Hens in undersized runs develop stress behaviors (feather-pecking, aggression) and have higher disease incidence. If you provide supervised free-range time, the run minimum can be reduced — but the coop indoor space cannot.
Roost Bar Space
Each hen needs 8–12 inches of linear roost bar space. Roosting is how chickens sleep — they don't nest in boxes overnight. Roost bars should be placed higher than nest boxes to discourage hens from sleeping (and soiling) the nesting areas. Round dowels or 2×4 lumber laid flat (wide side up) are both suitable.
Nest Boxes
Plan for one nest box per 3–4 hens. Standard nest box dimensions: 12"×12"×12" minimum. Hens don't each need their own box — they'll queue and share. More boxes than needed is fine; too few creates competition and egg-eating behavior.