Coop and run size for 20 chickens
These are common minimums from poultry extension guides. Bigger is better: crowded birds fight, peck and get sick, and most keepers add to their flock later. Plan for more birds than you start with.
| Item | Standard hens |
|---|---|
| Coop floor area (4 sq ft each) | 80 sq ft |
| Outdoor run (10 sq ft each) | 200 sq ft |
| Nesting boxes (1 per 4 hens) | 5 |
| Roost bar | 16.7 ft |
| Ventilation (about 1 sq ft each) | 20 sq ft |
| Feed per day (about 1/4 lb each) | 5.00 lb |
By breed size and run space
Bantams need less room than heavy breeds, and a roomier run keeps birds calmer and cuts down on bare ground and mud.
| Breed size | Run per bird | Coop floor | Run area |
|---|---|---|---|
| Bantams | 8 sq ft | 40 sq ft | 160 sq ft |
| Bantams | 10 sq ft | 40 sq ft | 200 sq ft |
| Bantams | 15 sq ft | 40 sq ft | 300 sq ft |
| Standard breeds | 8 sq ft | 80 sq ft | 160 sq ft |
| Standard breeds | 10 sq ft | 80 sq ft | 200 sq ft |
| Standard breeds | 15 sq ft | 80 sq ft | 300 sq ft |
| Large or heavy breeds | 8 sq ft | 100 sq ft | 160 sq ft |
| Large or heavy breeds | 10 sq ft | 100 sq ft | 200 sq ft |
| Large or heavy breeds | 15 sq ft | 100 sq ft | 300 sq ft |
Coop dimensions that give 80 sq ft
| Width | Length | Floor area |
|---|---|---|
| 3 ft wide | 26.7 ft long | 80 sq ft |
| 4 ft wide | 20.0 ft long | 80 sq ft |
| 5 ft wide | 16.0 ft long | 80 sq ft |
| 6 ft wide | 13.3 ft long | 80 sq ft |
| 8 ft wide | 10.0 ft long | 80 sq ft |
Use the chicken coop size calculator for your own flock, and read how big a chicken coop should be for ventilation and predator-proofing. Check local rules on flock size and distance from the property line.
Want to change anything else? The calculator above is the full Chicken Coop Size Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How big should a coop be for 20 chickens?
At least 80 sq ft inside for standard-size hens (4 sq ft each), such as 20.0 × 4 ft, plus a run of at least 200 sq ft at 10 sq ft per bird. Bantams need only 40 sq ft, and heavy breeds 100 sq ft.
How many nesting boxes for 20 chickens?
5 nesting boxes at one box for every 4 hens. Hens often share a favorite box, so extra boxes do not help.
How long should the roost be for 20 chickens?
About 16.7 ft of roost bar for standard hens (10 inches each), with 20 sq ft of ventilation opening high in the coop, away from the roost so there are no drafts on the birds.
Related sizes and guides
Related sizes
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.