Chicken Coop Calculator — Coop & Run Planner Suite

The widely used welfare minimum is 4 sq ft (0.37 m²) of indoor coop space per standard-sized chicken, plus 10 sq ft (0.93 m²) of outdoor run space per bird. Bantams need about 2 sq ft of coop + 4 sq ft of run, large/heavy breeds about 5 sq ft + 12 sq ft, and ducks about 4 sq ft + 15 sq ft of run. These figures are compiled from university extension guidance (for example, the University of Georgia Extension and Cornell Cooperative Extension coop guidelines). They are minimums — more space means less stress, less pecking, and easier cleaning. Note: if your birds have no run at all, plan on roughly 10 sq ft of coop per bird; free-range birds that only sleep in the coop can get by with about 3 sq ft each.

Plan on 10 sq ft (0.93 m²) of run per standard chicken — so 6 hens need a 60 sq ft run (for example 6 x 10 ft or roughly 1.8 x 3 m). Ducks appreciate more: about 15 sq ft each. The run calculator in this tool also lets you work backwards: enter your existing run's dimensions and it tells you how many birds it can hold, showing whether the coop or the run is the limiting factor. Remember the run must be predator-proof: use 1/2-inch hardware cloth (not chicken wire) on all sides, including a buried or ground-level apron to stop diggers.

An 8 x 6 ft coop (48 sq ft of floor) holds 12 standard chickens at the 4 sq ft minimum — but only if they also get at least 120 sq ft of run (10 sq ft each). Without any run, the same coop holds about 4-5 birds at the 10 sq ft coop-only minimum. Use the Reverse mode above: enter your coop's length and width (and run size if you have one) and it shows the maximum flock for your setup, and whether the coop or the run is limiting you.

Provide 1 nesting box per 4 hens — so 10 hens need 3 boxes, 12 hens need 3, and 15 hens need 4. Boxes should be about 12 x 12 x 12 inches (30 x 30 x 30 cm), mounted 18-24 inches off the floor, with a small perch or landing bar in front. Hens rarely all lay at once, which is why fewer boxes than hens works fine. Large breeds sometimes prefer a slightly roomier 14 x 12 inch box. Keep boxes lower than the roosts, or chickens will sleep (and poop) in them instead of on the roost bars.

Allow 10-12 inches (25-30 cm) of roost bar per standard or large-breed chicken and 8 inches (20 cm) per bantam. For 10 standard hens that is 100 inches — about 9 ft of bar, conveniently two 8-ft boards. Space multiple bars 12-18 inches apart horizontally and at least 12 inches from the wall, with the lowest bar 18-24 inches off the floor. Use 2x4 lumber wide-side-up (or a 2-inch round dowel): wide flat bars let birds cover their feet with their bellies in winter, which helps prevent frostbite. Never use metal or plastic bars — they are slippery and too cold.

A common rule of thumb is 1 sq ft of ventilation per 10 sq ft of coop floor — so a 48 sq ft coop needs about 4.8 sq ft of vent area (for example five 1 x 1 ft vents). Place vents high up, above roost level, so moist ammonia-laden air escapes without cold drafts blowing directly on sleeping birds. Keep vents open year-round, even in winter: cold fresh air is far less harmful than trapped moisture and ammonia, which cause respiratory disease and frostbite. Cover every vent with 1/2-inch hardware cloth to keep predators and rodents out.

A family of 4 eating about 1 egg per person per day needs roughly 28 eggs a week. At a typical lay rate of 5 eggs per hen per week (ISA Brown / Rhode Island Red type), that means 6 hens — plus room for winter dips when laying slows. The Flock Starter mode does this math for you: enter family size, daily egg appetite, and breed lay rate, and it recommends a flock size, then sizes the coop and run automatically. Start small: chickens are a multi-year commitment, and local ordinances often cap flock size (see below).

At the backyard minimum of 4 sq ft per bird, 1000 chickens need 4,000 sq ft of coop (for example 50 x 80 ft) plus 10,000 sq ft of run. But at that scale you are running a commercial operation, not a backyard flock — different rules apply (biosecurity, waste management, permits, and often dedicated ventilation and lighting systems). This tool is designed for backyard and small-scale flocks (roughly 2-50 birds). For commercial sizing, work with your state extension poultry specialist instead.

Switch the unit toggle above to Metric and every result converts automatically. Quick reference: 4 sq ft per chicken = 0.37 m²; 10 sq ft of run per chicken = 0.93 m². So 10 hens need about 3.7 m² of coop (for example 2.4 x 1.8 m) and 9.3 m² of run (for example 3.7 x 3 m). A standard 12 x 12 x 12 inch nesting box is 30 x 30 x 30 cm, and 10 inches of roost is 25 cm.

Bantams are small, so they need less room: about 2 sq ft (0.19 m²) of coop and 4 sq ft (0.37 m²) of run per bird — roughly half the standard recommendation. Ten bantams fit in a 20 sq ft coop (for example 4 x 5 ft) with a 40 sq ft run. Roost bars can be closer to 8 inches per bird, and 10 x 10 x 10 inch nesting boxes are fine. Note that bantams fly well, so runs for bantams should be fully covered.

A basic walk-in coop needs: floor joists (2x6 at 16-inch centers) + 3/4-inch plywood floor; wall studs (2x4 at 16-inch centers) with top and bottom plates; siding (T1-11 plywood sheets are the simplest; board-and-batten looks nicer); a roof (gable with asphalt shingles or metal panels); plus hardware cloth, screws, hinges, and paint. The Materials mode generates a full takeoff from your coop's dimensions — stud counts, board feet, plywood sheets, roofing, run posts, and hardware-cloth rolls — using standard framing math (studs at 16 inches on-center, 8-ft stick conversion for purchase quantities). The Cost mode then turns that list into a budget with editable unit prices.

It varies hugely by size, materials, and local lumber prices, but a small DIY walk-in coop for 6-10 hens typically costs a few hundred dollars in materials if you build from the Materials-mode takeoff with standard lumber and T1-11 siding. Premade coops of similar size often cost several times more. Use the Cost mode: it takes your computed materials list, applies editable default prices, and adds a 10% contingency. Always price-check against your local store — lumber prices move a lot by region and season.

Use hardware cloth (welded wire mesh, 1/2-inch grid), not chicken wire. Chicken wire keeps chickens in but does almost nothing against predators — raccoons can reach through it and tear it, and dogs, foxes, and weasels chew through it. Hardware cloth is stiffer, welded, and genuinely predator-resistant. Bury it 12 inches deep or lay a 2-ft ground apron around the run to stop diggers, and cover the top of the run against hawks and climbing predators. This is the single most important safety decision in coop building.

It depends entirely on your city, county, or HOA. Many US cities allow 4-6 hens (no roosters), some allow more on larger lots, and some HOAs ban poultry entirely — fines can be steep. There is no national database this tool could reliably query, so: check your city/county animal-control or zoning ordinances and your HOA covenants BEFORE building. The space math in this tool tells you what fits in your yard; the law tells you what is allowed. Roosters are the most commonly banned item, followed by flock-size caps and setback rules (often 15-25 ft from property lines).

You almost never need a coop heater — cold-hardy breeds handle well below freezing as long as the coop is dry and draft-free. What matters: keep ventilation open high up (moisture causes frostbite, not cold air), use wide 2x4 roost bars so birds cover their feet, keep water from freezing (a heated waterer base is safer than a coop heater), and do not overcrowd. Deep-litter bedding adds insulation and composting warmth. Coop heaters are a leading cause of coop fires; most extension guides advise against them.

The space and hardware numbers come from widely cited university extension guidelines (4 sq ft coop + 10 sq ft run per bird; 1 nesting box per 4 hens; 10-12 inches of roost per bird; 1 sq ft of vent per 10 sq ft of floor), and the materials math is standard framing arithmetic (studs at 16 inches on-center, board-foot conversion, 8-ft stick purchase quantities). It produces planning estimates, not engineering drawings — always check your local ordinances and HOA rules for backyard poultry, and adapt dimensions to your climate and breeds. Nothing here leaves your browser; all calculations run locally on your device.