Chicken Coop Size Calculator
Planning a flock? Enter how many chickens and this calculator sizes everything: coop floor space, run area, nest boxes, roost length and feeder space — using the standards experienced keepers swear by.
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You might also need:Aquarium Calculator·Dog Crate Size Calculator
The space standards
run = 10 sq ft × birds × breed · nests = birds ÷ 3.5 · roost = 11″ × birds
Six standard hens in full confinement: a 24 sq ft coop (say 6×4 ft), a 60 sq ft run (6×10 ft), two nest boxes and about 5½ feet of roost. Under-building is the classic first-flock mistake — crowded birds peck, and "chicken math" means you'll add more hens anyway. Build one size up.
Space per bird quick reference
| Element | Standard breed | Bantam |
|---|---|---|
| Coop floor | 4 sq ft | 2 sq ft |
| Run | 10 sq ft | 5 sq ft |
| Roost bar | 10–12″ | 6–8″ |
| Nest box | 1 per 3–4 hens | 1 per 3–4 hens |
| Feeder space | 3″ each | 2″ each |
Coop-building essentials
- Ventilation without draft: vents high above roost height, ~1 sq ft per 10 sq ft of floor — ammonia and moisture cause more illness than cold does.
- Predator-proof from day one: hardware cloth (not chicken wire — raccoons open that), buried aprons, and locks a clever raccoon can't flip.
- Build access for you: walk-in height or big clean-out doors — you'll be in there weekly.
- Building it yourself? Our construction site has the material math — framing, siding and roofing calculators at The Build Calculator.
Frequently asked questions
How much space do chickens need in a coop?+
The standard is 4 square feet per bird inside the coop for standard breeds, plus 10 square feet per bird in the outdoor run. Bantams need about half that; large breeds like Jersey Giants a bit more. If birds will spend snowy weeks locked in, be generous — crowding causes pecking.
How many nest boxes do I need?+
One nest box per 3–4 hens, at 12×12×12 inches each. Don’t be surprised when all of them queue for the same favorite box anyway — chickens have opinions.
How much roost space per chicken?+
Plan 10–12 inches of roost bar per standard bird, mounted higher than the nest boxes (or they’ll sleep — and poop — in the boxes). A 2×2 with rounded edges makes a perfect roost.
How many chickens should I start with?+
Three is the sensible minimum — chickens are flock animals and a lone bird is a sad bird. A family of four eats the eggs of 4–6 hens comfortably. Warning from everyone who keeps chickens: the flock only ever grows ("chicken math").
Do chickens need a run if they free-range?+
Yes — you still need a secure run for predator pressure, bad weather and days away. Free-ranging reduces how much run space gets used, not whether you need it. Bury hardware cloth 12 inches or skirt it outward to stop diggers.