Size by flock
Coop size for 12 chickens
For 12 standard-size hens: 48 sq ft of floor (4.5 m²), a 120 sq ft run (11.1 m²), 120 inches of roost and 3 nest boxes. Here is what that looks like in practice.
The plan
| Item | Minimum | Suggested shape |
|---|---|---|
| Coop floor | 48 sq ft · 4.5 m² | about 6.9 × 6.9 ft (2.1 × 2.1 m) |
| Run | 120 sq ft · 11.1 m² | about 7.7 × 15.5 ft (2.4 × 4.7 m) |
| Roost bar | 120 in · 3.0 m | a 10 ft 2×4, wide side up |
| Nest boxes | 3 | 12 × 12 in |
| Feeders and waterers | 2 of each | one extra waterer in summer |
Why these numbers
They are the minimums extension offices and most experienced keepers use: 4 sq ft of coop and 10 sq ft of run per standard hen, 8 to 10 inches of roost, one nest box per 3 to 4 hens. A crowded coop is the number one cause of feather picking, bare backs and broken eggs.
If your hens are not standard size
Bantams (Silkies, Sebrights): 24 sq ft of coop and 72 of run. Large breeds (Orpington, Brahma, Jersey Giant): 60 and 144.
Before you build
- Ventilation up high, no drafts down low. Half-inch hardware cloth on every opening, never chicken wire.
- Roosts higher than nest boxes, or they will sleep in the boxes and foul the eggs.
- A walk-in coop saves your back every single week.
- Build for 14: chicken math is real.
- Check your city and HOA rules on flock size and setbacks before buying lumber.
Kit makers often overstate how many hens fit, so compare the floor size on the listing with your number. Big kits don’t always ship to Puerto Rico, Hawaii or Alaska.
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Change the breed or the count in the coop size calculator.
Common questions
What size coop do I need for 12 chickens?
At least 48 sq ft of floor (4.5 m²) for standard breeds, plus a 120 sq ft run (11.1 m²). More is always better.
How many nest boxes for 12 chickens?
3. One box per 3 to 4 hens; they will all use the same one anyway.
Can 12 chickens live in the coop with no run?
Only if the coop is sized as coop and run combined, about 168 sq ft, with light and ventilation. A 48 sq ft coop is a bedroom, not a home.
What about bantams or large breeds?
Bantams: 24 sq ft of coop and 72 of run. Large breeds (Orpington, Brahma): 60 and 144.