How big a coop do your hens need?

What this calculator does, and why it shows ranges

There is no single national standard for how big a backyard chicken coop must be. University extension services publish advice, and the numbers differ from one publication to the next. Instead of picking one and calling it the answer, the calculator takes the number of hens and shows the lowest and highest figure printed in five publications: Penn State Extension, Oregon State University Extension, Colorado State University Extension (Boulder County), the University of Georgia Cooperative Extension and Oklahoma State University Extension. Below the answer every figure is listed with the name of the publication that printed it. No number on this page comes from anywhere else.

How the totals are found

Floor, run, roost and feeder amounts are the per-bird figure times the number of hens; roost and feeder inches are divided by 12 for feet. Nest boxes are the number of hens divided by the hens one box serves, rounded up, for each publication, and the answer is the smallest and the largest count. Penn State states its rule differently, two nests for the first four hens and one more for each four after that, so it is calculated that way. Feed uses Oklahoma State's figure of 0.25 pound a day for a mature hen and water uses Georgia's statement that 20 hens drink about 1 gallon a day in cool weather. The breed menu changes one row only: Colorado State's table for birds 12 weeks and older gives 2.5–3 square feet per bird for lightweight breeds and 3–3.5 for heavy breeds, against its general range of 2–4.

Worked example: six hens

With six hens and a run, the coop floor works out to 9–24 square feet. The lowest figure is Oklahoma State's 1.5 square feet per hen (9 square feet), and the highest is Colorado State's general upper figure of 4 (24 square feet). Choose heavy breeds and the range narrows to 9–21 square feet, because Colorado State's heavy-breed row tops out at 3½. The run takes 36–60 square feet (6 to 10 per bird). Roost length is 2.5–6 feet (5 to 12 inches per bird), and 2–3 nest boxes of 12 × 12 inches do for six hens. Feed comes to 1.5 pounds a day and water about 0.3 gallon. If the six hens have no outdoor run, Oregon State asks for 8 to 10 square feet of coop floor per bird, which is 48–60 square feet. A flock of 12 doubles the floor to 18–48 square feet, and the nests become 3–4.

What each publication prints

These are the figures from the five documents, in the order the calculator uses them.

Penn State (Successfully Raising a Small Flock of Laying Chickens, April 22, 2016): coop floor 2 ft² per bird; roost 6 inches per bird; two nests for the first four hens, then one more for every four additional hens; feeder space 3 inches per bird.
Oregon State (EC 1644, Living on the land: Backyard chicken coop design, April 2014, reviewed 2023): coop floor 3 ft² per bird (at least, with access to a run); 8–10 ft² per bird of coop floor if there is no outdoor access; roost 5–10 inches per bird; one nest box for every 4 hens.
Colorado State (Backyard and Small Flock Poultry in Boulder County, Revision 1, 2020): coop floor 2–4 ft² per bird (depending on breed size; lightweight breeds 2.5–3, heavy breeds 3–3.5, for birds 12 weeks and older); run 6–10 ft² per bird (based on breed size); roost 6–12 inches per bird (based on breed size); one nest box for every 3–4 hens.
Georgia (Circular 969, Management Guide for the Backyard Flock, revised June 2009): coop floor 3–3.5 ft² per bird (for each bird kept for eggs); one nest box for every 4–5 hens; feeder space 4–6 inches per bird.
Oklahoma State (AFS-8202, Backyard Flock Production, March 2017): coop floor 1.5–2 ft² per bird (depending on bird size); run 8–10 ft² per bird (depending on bird size; printed as “feet”); one nest box for every 4 hens; a laying hen eats about 0.25 pound of feed a day.

Limits of these numbers

The five documents come from Oregon, Pennsylvania, Colorado, Georgia and Oklahoma, were written for different purposes and are dated between 2009 and 2023, so the spread between them is real and the calculator does not hide it. Penn State's 2 square feet is for indoor space and gives no run figure, Oklahoma State's 1.5 to 2 is inside the house with the run listed separately, and Oregon State's 3 square feet applies when the birds have a run; without outdoor access Oregon State asks for 8 to 10. Oklahoma State prints its run figure as “8 to 10 feet per bird,” without the word square; it is read here as square feet because Colorado State gives 6 to 10 square feet for the same thing. The Colorado State area table is broken across lines in the PDF's text, so its rows were matched to the ages by order. None of the five has a separate row for bantams, and none prints a number for ventilation: they ask for windows or vents without drafts, and Oklahoma State suggests openings on one or two sides, away from the winter winds. Nothing here covers predators, snow load, heat or the climate where you live. Check your local zoning, city and homeowner association rules before you build; Georgia and Oklahoma State both list this as a first question.

How big should a chicken coop be for 6 chickens?

The publications ask for 1.5–4 square feet of coop floor per hen when the birds have an outdoor run, which is 9–24 square feet for six hens, plus a run of 36–60 square feet. A 4 × 6 foot coop, 24 square feet, is at or above every figure printed for six hens. Without a run Oregon State asks for 8 to 10 square feet per bird.

How much run space does a chicken need?

Colorado State Extension gives 6 to 10 square feet per bird based on breed size, and Oklahoma State gives 8 to 10 depending on bird size, though it prints the unit as “feet”. That is 36–60 square feet for six hens. Oregon State's EC 1644 does not give a run area, only the coop floor figure with and without outdoor access.

How many nest boxes do I need?

Oregon State and Oklahoma State say one box for about every four hens, Colorado State one for every three to four, and Georgia one for every four to five. Penn State asks for two nests for the first four hens and one more for each four after that. For 12 hens that is 3–4 boxes. Four of the five give a size, 12 × 12 inches (Oregon State and Colorado State 12 inches tall too); Penn State says at least 12 × 12.

How much roost space does a chicken need?

Penn State asks for 6 inches per bird, Oregon State for 5 to 10 inches, and Colorado State for 6 to 12 inches depending on breed size. Penn State places roosts 18 to 24 inches above the floor, about a foot apart; Oregon State sets them 2 feet off the floor with 10 inches between poles. For six hens the roost is 2.5–6 feet.

How much ventilation does a coop need?

None of the five publications gives a number. Oregon State says passive ventilation through windows or vents is adequate for most backyard coops and to build in as much as possible without drafts; Penn State says to limit drafts and moisture; Oklahoma State says windows or vents on one or two sides usually provide plenty for a small coop, placed away from prevailing winter winds, the south or east side being best. Colorado State asks for a coop that is free of drafts but can be ventilated well in hot months.

Do bantams need less space than standard chickens?

The documents used here do not say. Colorado State separates lightweight and heavy breeds, and Oklahoma State and Colorado State tie their ranges to bird size, but none gives a bantam row. Georgia says the minimum space depends on the type of bird, from ¾ to 1 square foot for smaller breeds to 3 to 4 for turkeys, and gives 3 to 3½ square feet as a good rule for each bird kept for eggs. Ask your local extension office before sizing a coop for bantams.

How much do chickens eat and drink?

Oklahoma State describes a mature hen as eating about 0.25 pound of feed a day, so six hens use 1.5 pounds a day. Georgia says 20 hens drink about 1 gallon of water a day in cool weather, and that consumption rises sharply in hot weather. These are single figures from single publications, so the calculator shows them but does not turn them into a feed budget.

Can I keep chickens in my backyard?

That depends on local rules, which this page cannot know. Georgia's Circular 969 starts with checking whether zoning regulations prohibit raising poultry on your property, and Oklahoma State's fact sheet asks whether there are city ordinance or homeowner association restrictions. Ask your city or county and your HOA before you buy birds or build.

Sources: Penn State Extension, “Successfully Raising a Small Flock of Laying Chickens” (updated April 22, 2016); Oregon State University Extension, EC 1644 “Living on the land: Backyard chicken coop design” (April 2014, reviewed 2023); Colorado State University Extension, Boulder County, “Backyard and Small Flock Poultry in Boulder County” (Revision 1, 2020); University of Georgia Cooperative Extension, Circular 969 “Management Guide for the Backyard Flock” (revised June 2009); Oklahoma State University Extension, AFS-8202 “Backyard Flock Production” (March 2017), all read October 27, 2026. The totals are arithmetic on those figures. Related: raised bed soil calculator for the garden next door, lawn watering calculator, fence calculator for the run and square footage calculator for the footprint. How we check our calculators.