Tool
Chicken Coop Space Calculator: Square Feet, Roosts and Nest Boxes per Hen
How big does a coop need to be for your hens? Enter how many full-size and bantam-size hens you keep and whether they have an outdoor run. The calculator turns published university extension figures into floor area, run area, roost length, nest boxes and feeder and waterer space. Because the sources disagree, it shows a minimum and a roomier figure rather than one number.
- Roost length–
- Nest boxes (12 × 12 in)–
- Feeder space–
- Waterer space–
Planning figures from extension publications, not a legal or welfare standard. Check local ordinances, and give more room if birds are confined for long stretches.
How the calculator works
The calculator multiplies the number of hens by the per-bird figures below and adds full-size and bantam-size birds together:
Coop floor, with a run = full-size hens × 1.5 to 3 sq ft + bantams × 0.75 to 1 sq ft
Coop floor, no outdoor access = all hens × 8 to 10 sq ft
Run = all hens × 4 to 10 sq ft
Roost = all hens × 5 to 10 in · Nest boxes = all hens ÷ 4, rounded up
Feeder = all hens × 3 to 6 in · Waterer = all hens × 1 in
| Input | Value used | Where it comes from |
|---|---|---|
| Coop floor, full-size hen with run access (minimum) | 1.5 sq ft | Penn State: "at least 1.5 square feet per hen"; Oklahoma State: 1.5 to 2 sq ft per bird inside the house, depending on bird size |
| Coop floor, full-size hen with run access (roomier) | 3 sq ft | Oregon State: at least 3 sq ft per bird if there is access to a run; Cornell (Warren County) 2.5–3.5; Georgia 3–3½ for egg production |
| Coop floor, bantam-size hen | 0.75–1 sq ft | Georgia: small breeds such as Rosecomb or Sebright, about 1.3 to 1.5 lb, need 0.75 to 1 sq ft per bird |
| Coop floor, no outdoor access | 8–10 sq ft | Oregon State: 8 to 10 sq ft per bird if there is no outdoor access |
| Run or yard | 4–10 sq ft | Cornell (Warren County): an additional 4 to 5 sq ft outside; Penn State: 5–10 sq ft in an exercise area; Oklahoma State: 8 to 10 per bird in the run |
| Roost | 5–10 in per bird | Oregon State: 5 to 10 inches of pole per bird; Penn State: 6 linear inches |
| Nest boxes | 1 per 4 hens | Oregon State, Oklahoma State and Penn State: one nest for about every four hens; Georgia: one for every four to five; Maine: at least one for every five |
| Feeder | 3–6 in per bird | Penn State: 3 inches; Georgia: 4–6 inches |
| Waterer | 1 in per bird | Penn State and Georgia: 1 inch of drinking space per bird |
Two choices here are ours rather than the sources': no extension source we read gives separate coop-only or run figures for bantams, so the calculator applies the full-size figures to them in those cases, and it uses Cornell's 4 sq ft as the low end for a run. Both choices err toward more space, not less.
Where the sources disagree
Extension recommendations for floor space range from 1.5 to 3½ square feet per laying hen when birds also go outdoors. Some of that spread reflects bird size — Georgia ties its figures to body weight, from about 1.3 lb for small breeds to 7.5–8 lb for large breeds such as Orpington or Plymouth Rock, which it gives 3 to 3.5 sq ft — and some reflects whether a figure is a bare minimum or a comfortable target.
| Source | Inside the coop | Outdoor run or yard |
|---|---|---|
| Oregon State (EC 1644) | At least 3 sq ft with run access; 8–10 sq ft with none | — |
| Penn State | At least 1.5 sq ft per hen | 5–10 sq ft per bird if birds are confined to an exercise area; yards "are not necessary" |
| Oklahoma State (AFS-8202) | 1.5–2 sq ft per bird, by bird size | 8–10 per bird |
| Cornell Cooperative Extension, Warren County | 2.5–3.5 sq ft minimum | An additional 4–5 sq ft |
| University of Georgia (Circular 969) | 3–3½ sq ft per laying bird; ¾–1 sq ft for smaller breeds | — |
| University of Maine 4-H | 2–3 sq ft per bird, which could include an outside run | — |
Fitting out the coop
- Vent high on the wall, on the side away from prevailing winter winds (Oklahoma State).
- Roost poles about 2 ft off the floor and 10 in apart, with 5–10 in of pole per bird (Oregon State).
- Nest boxes about 12 × 12 × 12 in, raised about 2 ft with a landing perch in front, one per four hens (Oregon State, Georgia).
- Feeder and waterer: 3–6 in of feeder and 1 in of drinking space per bird (Penn State, Georgia).
- Floor: 1.5–3 sq ft per full-size hen when birds also use a run (Penn State, Oregon State).
- Run: 4–10 sq ft per bird (Cornell, Penn State, Oklahoma State).
- Nest boxes. Oregon State gives each box as about 12 inches deep, wide and tall. Georgia suggests raising boxes about 2 feet off the ground with a perch about 4 inches in front of each, and Oklahoma State says nests should sit in a dark part of the house. Penn State calls for a minimum of four nest boxes and at least one 12-by-12-inch nest for every four hens.
- Roosts. Oregon State sets poles about 2 feet off the floor with 10 inches between poles, and only 1 foot up for Silkies. Penn State describes 2-by-2 boards spaced 12 inches apart and 24 inches above the floor.
- Feeders and water. Oklahoma State says there should be enough feeder space for every bird to eat at the same time. A nipple waterer bucket is one way to keep water clean.
- Ventilation. Oregon State says ventilation removes ammonia, carbon dioxide and moisture, and passive vents are adequate for most backyard coops. Oklahoma State advises putting windows or vents on the sides away from prevailing winter winds, with the south or east side best.
Chicks need less — for now
Penn State says chicks can start in a smaller brooder at 0.5 square foot per bird for the first 6–8 weeks; Georgia notes that a brooder ring about 6 feet across gives plenty of room for 50 chicks. Plan the coop for the adult flock, though: by the time pullets move out of the brooder they need full adult space. For brooder temperatures and safer heat, see heat lamps and brooding chicks.
Planning checklist
- Count the hens you plan to keep at the flock's largest, including pullets you expect to add.
- Decide whether birds will have daily outdoor access. If not, use the coop-only setting — the per-bird figure rises from about 1.5–3 to 8–10 sq ft.
- Pick a coop at or above the roomier figure if you can; the minimum is a floor, not a target.
- Check that the roost length, nest count and feeder space fit inside the footprint.
- Confirm local rules on flock size and coop placement before you build.
- Compare your hen count against the eggs you need with the egg production calculator.
Sources
- Oregon State University Extension — Living on the Land: Backyard Chicken Coop Design (EC 1644)
- Penn State Extension — Management Requirements for Laying Flocks
- Oklahoma State University Extension — Backyard Flock Production (AFS-8202)
- University of Georgia Cooperative Extension — Management Guide for the Backyard Flock (Circular 969)
- University of Georgia Cooperative Extension — Housing and Confinement for the Backyard Flock
- Cornell Cooperative Extension, Warren County — Backyard Chickens
- University of Maine Cooperative Extension 4-H — Housing Your Pullets