Free tool
Chicken coop size calculator
How much space does your flock actually need? Enter the number of birds and their size for the recommended minimum coop floor, run, nesting boxes, and roost length.
Where these numbers come from
The per-bird figures are the space minimums commonly recommended by poultry extension services — roughly 4 sq ft of coop floor and 8–10 sq ft of run per standard-sized bird, with bantams needing less and large or heavy breeds needing more. See Poultry Extension for the underlying guidance.
⚖️ The honest caveat
There is no single “correct” number, and any calculator that pretends otherwise is overselling it. These are floors, not targets — more space is always better, and the real requirement shifts with your breed, climate, and how long the birds are confined. A flock locked in the run all winter needs far more room than one that free-ranges the yard all day. Treat the result as the absolute minimum to design above, and when in doubt, build bigger: crowding is the single most common cause of pecking, disease, and stress in a backyard flock.
Keep going
Once you’ve sized the space, get the inside right: our nesting box guide covers box sizing and placement (and how to stop floor eggs), the coop bedding comparison covers what goes on the floor, and the temperature guide covers ventilation and heat — which matter more than raw square footage for a healthy flock.