Chicken Coop & Run Calculator
How much coop and run a flock actually needs, plus nesting boxes, roost length, feeder and water, and how long a bag of feed lasts, all worked from US cooperative extension guidelines. More room is always better, so treat these as minimums.
Check a coop you are planning
How the numbers are set
Coop floor space scales with flock size: about three and a half square feet per standard hen with access to a run, one for a bantam, four for a heavy breed. Run space is about ten square feet per hen, far more for genuine free-range pasture. Nesting boxes run one per four hens, roosts about eight to ten inches of bar per bird, feeders about three inches of trough each. A laying hen eats roughly a quarter pound of feed and drinks about a pint of water a day, and in hot weather she drinks twice that.
Ventilation and winter, honestly
There is no single per-bird ventilation number worth trusting. The rule that works: vent high near the roofline, keep it draft-free down at roost level, and if windows or walls show condensation in the morning, add more. Moisture, not cold, is what harms chickens. Most standard backyard breeds are cold-hardy and do not need a heated coop, and extension services widely discourage coop heaters as a fire risk. The one winter add-on worth it is a heated waterer, because water freezes at thirty-two degrees and birds cannot drink ice.
Sources
Space, perch, feeder, feed and water figures: poultry.extension.org (the US Cooperative Extension poultry resource), Penn State Extension, University of Minnesota Extension, University of Georgia Extension, and Alabama Cooperative Extension. Pasture stocking: Certified Humane. Ranges are given where extensions disagree; roost length spans six to twelve inches per bird, and there is no agreed temperature for supplemental heat.