Chicken Coop Size Calculator
Calculate the right chicken coop and run size for your flock.
Find square footage per bird, roost bar length, nesting box count, and ventilation area for healthy backyard chickens.
Coop Space Requirements Overcrowding is the #1 cause of disease, pecking, and stress in backyard flocks. Minimum coop floor space: Standard breeds (Rhode Island Red, Orpington, Plymouth Rock): 4 sq ft (0.37 m²) per bird inside Large/heavy breeds (Jersey Giant, Brahma): 5–6 sq ft per bird Bantam breeds (Silkie, Sebright): 2 sq ft per bird Cold climates where birds spend long periods inside: add 25–50%
Run / Outdoor Space Attached outdoor run: Standard breeds: 10 sq ft (0.93 m²) per bird minimum; 15–20 sq ft ideal Free range / large paddock: 250+ sq ft per bird Confined run with no free range: at least 15 sq ft per bird to prevent boredom
Roost Bars Chickens sleep perched on roost bars, not on the floor. Space per bird: 8–12 inches (20–30 cm) of roost length per bird Position: at least 18" from walls and 12" apart if multiple levels Height: 18–24" above floor minimum; not too high to prevent leg injuries on dismount
Nesting Boxes 1 nesting box per 4–5 hens (hens share boxes — they take turns). Size: 12" × 12" (30 × 30 cm) for standard breeds; 14" × 14" for large breeds. Position: lower than roost bars (so hens don’t sleep in them). Provide fake eggs (golf balls) to encourage use.
Ventilation Minimum: 1 sq ft of ventilation per 10 sq ft of floor space. Ammonia from droppings damages lungs — ventilation is critical even in winter. Vents near the top of the coop; draft-free at roost level. Deep litter method: 4–6" of bedding (pine shavings, straw) absorbs droppings.