Chicken Coop Size Calculator
Get coop floor space, run space, roost bar length, and nest box count for your flock size, standard or bantam.
These are minimums. More space than this means fewer pecking-order problems, and if your birds spend long stretches cooped up in a cold climate, give them extra room beyond these numbers.
How it works
Enter how many birds you keep and whether they're standard breeds or bantams, and the calculator applies the space guidelines most keepers and extension offices use. Standard hens need about 4 sq ft of coop floor and 10 sq ft of run each; bantams are roughly half that, at 2 sq ft of coop and 5 sq ft of run. Roost bar scales at about 10 inches per bird regardless of size, since birds of any breed still need room to perch shoulder to shoulder without crowding. Nest boxes are figured at one box per four hens, with a minimum of one box even for a single bird.
Worked example: 6 standard hens need 24 sq ft of coop floor, 60 sq ft of run, 60 inches of roost bar, and 2 nest boxes. Bump that to 10 hens and the coop floor grows to 40 sq ft and you'll want a third nest box, since 10 divided by 4 rounds up past 2. Switch the same 6 birds to bantams and the footprint shrinks to 12 sq ft of coop and 30 sq ft of run, though roost length and nest box count stay the same since those depend on bird count, not size.
FAQ
Are these numbers a hard minimum or a comfortable target?
They're minimums. Chickens that are packed to the exact square footage tend to squabble more, peck at each other's feathers, and get stressed during molt or bad weather when they're stuck inside longer than usual. If your yard allows it, give birds more than the calculator suggests, especially the run space.
Do I need more space in a cold climate?
Yes. Birds that spend most of a long winter in the coop rather than free-ranging in the run benefit from extra floor space beyond the minimum here. A coop sized exactly to the summer minimum can feel cramped and lead to feather-picking once everyone's stuck inside for weeks at a time.
Why does roost length matter separately from floor space?
Chickens roost shoulder to shoulder at night, and a coop can have plenty of floor area but not enough roost bar, which leads to birds fighting over perch space or sleeping on the floor in droppings. Ten inches per bird gives each hen room without birds piling on top of each other.
What if I keep a mix of standard and bantam breeds?
Run the calculator once for your standard birds and once for your bantams, then add the two coop and run figures together. Roost inches and nest boxes can be combined the same way, since both scale with total bird count rather than breed size.
For more on sizing and setting up the space itself, see how big should a chicken coop be, nesting boxes: how many, what size, and where to put them, and roosting bars, setup and why chickens need them.