Chicken Coop Size Calculator
Enter your flock and get the space numbers that experienced keepers and university extension services actually recommend — not the capacity printed on a coop box. Then take the numbers to our coop buying guides.
Your recommended setup
| Coop interior floor | |
|---|---|
| Run space | |
| Roost bar length | |
| Nest boxes | |
| Feeder space (linear) | |
| Water per day |
The math behind the numbers
- Coop floor: ~4 sq ft per standard bird with run access (3 bantams, 5 large breeds). Without daily run access, plan 8–10 sq ft per bird inside.
- Run: ~10 sq ft per bird; free-range flocks can go a little smaller, confined flocks bigger.
- Roost: 8–12 inches of bar per bird.
- Nest boxes: one box per 4 hens.
- Water: roughly 1 gallon per 4–5 birds per day; more in heat, less in cold.
These are widely used rules of thumb for planning, not veterinary advice — bantams, climate and breed temperament all shift the numbers. Sources: eXtension — space allowances (3–4 sq ft indoor, 10 sq ft outdoor), Penn State Extension — small flock guide (the low end of the published range), and large keeper communities (BackYardChickens.com, r/BackYardChickens).