Chicken Coop Size Calculator
Find how many square feet of coop and run, how many feet of roost, and how many nest boxes your flock needs, with a suggested footprint to build.
Free · no account · works on mobile · embeddable
Best for backyard and small-flock keepers planning or expanding a coop. Updated .
Your flock
Space to build
Ventilation: Virginia Tech's guide calls ample air movement without a draft essential. Put vents high on the walls above roost height, on more than one side, and screen them with hardware cloth. Damp litter and an ammonia smell mean the coop needs more air, not more birds.
Coop sq ft = birds × sq ft per bird for the size class and housing style. Run = birds × run sq ft. Roost ft = birds × inches ÷ 12. Nest boxes = birds ÷ 4, rounded up. A hobbyist and small-flock tool; commercial housing follows different standards.
About the chicken coop size calculator
Coops are almost always built too small, and crowded birds peck, pile, and stop laying. This calculator turns your flock count, bird size, and housing style into the floor space, run area, roost length, and nest boxes that extension housing guides recommend, then suggests a builder-friendly footprint such as 6 x 6 or 8 x 12 that meets the floor requirement.
It is a hobbyist and small-flock tool. Commercial layer and broiler housing follows different standards and is not what these figures describe.
Space per bird
Virginia Cooperative Extension's small-scale housing guide gives bantams 2 to 3 sq ft inside and 5 to 8 sq ft of run, and laying hens or meat-type chickens 3 to 4 sq ft inside and 10 sq ft of run each. Oregon State Extension's coop design guide says at least 3 sq ft per bird with access to a run and 8 to 10 sq ft per bird with no outdoor access. The presets take the low end for bantams, the low end of the laying-hen range (3 sq ft) for standard breeds, and the top for heavy breeds, and switch to the confined figures when you choose confined housing.
Roosts, nests, and ventilation
Virginia Tech recommends 8 to 10 inches of perch per laying bird and one nest for every 4 to 5 hens; Oregon State allows 5 to 10 inches of roost per bird and one nest box for about every four birds. The calculator uses one box per four hens and a per-bird roost length by size class. Meat birds do not need nests but do use low perches.
Ventilation has no formula here, but both guides treat it as essential: ample air movement without a draft. Put openings high on the walls above the roosts, on more than one side, and cover them with hardware cloth. Damp litter or an ammonia smell means the coop needs more air, not fewer birds.
Worked example: 12 standard hens with a run
12 standard laying hens with a run need 3 sq ft each inside, or 36 sq ft of coop floor, and 10 sq ft each of run, or 120 sq ft. Roost length is 12 × 8 inches, or 8 ft. Nest boxes are 12 ÷ 4, or 3. The suggested footprint is 6 x 6 ft, which is 36 sq ft. Switch to confined housing and the same flock needs 8 sq ft each, 96 sq ft, with an 8 x 12 footprint.
Sources
- Virginia Cooperative Extension, Small-scale poultry housing (2902-1092). Bantams 2 to 3 sq ft inside and 5 to 8 sq ft of run; laying hens and meat-type chickens 3 to 4 sq ft inside and 10 sq ft of run; 8 to 10 inches of perch per laying bird; one nest per 4 to 5 females. Accessed Sep 4, 2026.
- Oregon State University Extension, Living on the land: backyard chicken coop design (EC 1644). At least 3 sq ft per bird with a run and 8 to 10 sq ft per bird with no outdoor access; 5 to 10 inches of roosting pole per bird; one nest box for about every four birds. Accessed Sep 4, 2026.
This calculator gives planning estimates from the numbers you enter. It is not accounting, tax, veterinary, or legal advice. Replace the defaults with your own farm records whenever you have them.
Frequently asked questions
How many square feet does a chicken need in a coop?
About 3 to 4 sq ft per standard hen inside when the flock has a run, and 8 to 10 sq ft per bird if they are confined to the coop. Bantams need about 2 to 3 sq ft with a run. More is better; these are minimums from extension housing guides.
How big should a chicken run be?
About 10 sq ft per standard chicken and 5 to 8 sq ft per bantam. A 12-hen flock therefore wants roughly 120 sq ft of run, for example 10 x 12 ft. Free-ranging birds can get by with a smaller secure run for bad weather.
How many nesting boxes do I need?
One nest box for every 4 to 5 hens. Twelve hens need three boxes; twenty need four or five. Hens will crowd into a favorite box regardless, so extra boxes rarely get used.
How much roost space does a chicken need?
About 8 to 10 inches of roost per standard laying hen and 6 inches or so per bantam. Round poles or 2x4s with the wide side up work well, set 18 to 24 inches off the floor with room between roosts so birds do not sit under one another.
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