Coop floor
1.5 to 4 sq ft per standard hen
How the coop is sized for bantams, standard and large breeds, and why the figures differ between universities.
Space per henFree backyard coop calculator
How big does your chicken coop need to be?
Tell it how many hens and what size. You get the coop floor, the run, roost length and nest boxes right away, sized from published university extension guidance, with the ranges shown.
- Where universities disagree, we show the range and say which end we size on.
- A floor plan drawn to your numbers, plus vent areas and a materials estimate in the full calculator.
- Free. Runs in your browser. No sign-up to use it.
Size my coopLive result
What it sizes
Six things to get right before you buy lumber
Each figure comes from extension publications from Penn State, Minnesota, Oregon State, Utah State, Virginia Tech, Kentucky, Mississippi State, Cornell and others. The guides show every source.
Run
2 to 10 sq ft per standard hen
Outdoor space that keeps a run from turning to mud, with fence widths that use standard rolls and posts.
Worked examplesRoosts and nests
5 to 10 in of roost, 1 nest per 4 to 5 hens
Bar length, height and spacing, plus nest box count, size and the height that keeps hens out of them at night.
Roost guideVentilation and predators
6 sq in of inlet per 25 sq ft of floor
Air that moves above the birds, not across them, and 1/2 in hardware cloth with a buried apron.
Ventilation guideCost estimate
Quantities first, then your local prices
Panels, boards, mesh and roofing counted from your sizes, priced with wide ranges you can edit.
Estimate methodCoopSizer Plans
Drawn to your flock
Four dimensioned drawings, a materials list, a cut list for every 2x4 and twelve build steps, from the sizes above. From $19.
See the plansRecent guides
Plain answers, with the source named
How Much Space Do Chickens Need? Coop and Run, by the Numbers
Coop and run space per hen from ten university extension sources, why the numbers differ, and how to pick a figure for bantams, standard and large breeds.
How Many Nesting Boxes Per Hen? Ratios, Sizes and Placement
One nest box per four to five hens is the extension rule. Here is how to round it, how big each box should be, how high to mount it and what goes inside.
Roost Bar Spacing and Height: Inches Per Bird, Gaps and Lumber
How much roost each hen needs, how high to set the bars, how far apart, and what lumber to use, with the ranges from six extension publications.
Chicken Coop Ventilation Without Drafts
How much vent area a coop needs, where to put the openings so air moves above the birds and not across them, and how winter and summer needs differ.
Free, by email
Get the printable coop checklist
One page to take to the lumber aisle and the build site. Every number on it comes from university extension guidance, with the source named.
- Floor space per hen, coop and run
- Roost inches, height and spacing
- Nest boxes: count, size, height
- Vent areas for winter and summer
- Hardware cloth, apron and night lockup
- Ordinances and setbacks to check first
Available now
CoopSizer Plans
Coop plans generated from your flock: the size the calculator gives you, drawn out as a floor plan, two elevations and a section, with a materials list, a cut list for every 2x4 and twelve build steps. Prints to scale as a PDF.
30-day refund, see the terms. Plans are generated from your inputs and published extension guidance. They are not engineered drawings. Check local building codes, HOA rules and ordinances. Build at your own risk.
- Drawings at your coop and run size, with dimensions in feet and inches, not a fixed 4 x 8.
- Materials list with quantities: panels, boards, mesh, roofing, hinges, screws.
- Cut list for every 2x4 with a board-by-board diagram, using actual lumber sizes.
- Roosts, nest boxes, vents and the buried apron placed to extension guidance.