Build your flock bird by bird — bantams to Jersey Giants, roosters, even ducks — pick your housing style and climate, and get the full housing spec: coop square footage with a suggested footprint, run size, nesting boxes, roost length, ventilation, and your estimated egg basket per week.
Flock Housing Planner
Space figures follow widely accepted husbandry guidelines: ~4 sq ft of coop floor and ~10 sq ft of run per standard bird, one nesting box per 3–4 hens, and roughly 1 sq ft of ventilation per 10 sq ft of floor. More space is always better — these are working minimums for a healthy, low-stress flock.
Each bird class carries its own space requirements: bantams get by on 2 sq ft of coop floor while a Jersey Giant needs 5, and ducks — floor sleepers with big footprints — need 5 sq ft inside plus 15 in the run. Housing style shifts the math: free-range flocks that only sleep inside need a bit less, while a flock confined to the coop full-time needs its indoor number doubled. Cold climates add 25% indoor space because birds shelter inside for days at a stretch, and hot climates bump ventilation 50%. Nest boxes calculate at one per 3–4 hens (ducks get ground-level corners instead), roosts at 6–12 inches per bird by size, and the egg estimate uses typical per-breed-class weekly averages for hens in their productive years.
Most coop calculators treat every chicken as identical. In reality, packing Brahmas into a coop sized for Leghorns is how you get feather-pecking, frostbitten combs from overcrowded roosts, and stress-driven egg drops. Mixed flocks are the norm on real homesteads — a few bantams, a heavy broody, a rooster, maybe ducks sharing the run — so this calculator sizes each bird for what it actually is, and warns you when the rooster math doesn’t work out.
Take your numbers to the buying guide for the deeper walkthrough, then browse the style that fits: small backyard coops, coops with integrated runs, walk-in barns, mobile tractors, easy-clean plastic designs, or elevated coops. More build walkthroughs live on The Roost. And whatever you buy or build: real ventilation, half-inch hardware cloth everywhere, and one size bigger than you think you need. Chicken math is real — every flock grows.