Coop size calculator — how many birds fit, and how big to build

Give it a coop size and it tells you how many birds belong in it. Give it a flock and it tells you how big to build. It also sizes the run, the roost, the nest boxes and the feeder, which is where crowding actually bites first.

Space per bird, by species

These are the figures for birds shut in overnight with access to a run by day. Birds confined full time need roughly double the coop floor — the space standard exists to prevent feather-picking and cannibalism, and those start with boredom as much as with density.

Crowding shows up at the feeder first

Floor space is the number everyone quotes and rarely the one that breaks. A flock with enough floor but not enough feeder frontage eats in shifts, and the birds at the bottom of the pecking order eat last and least. You see it as uneven weights and a couple of birds going bare-backed, weeks before the floor looks crowded.

The same is true of roost bar. Birds that cannot all get up will sleep in the nest boxes, and a nest box slept in is a nest box fouled — which is how a clean flock starts producing dirty eggs for no obvious reason.

What the run is actually for

Run space is not exercise, it is ground recovery. A run stocked at the figures above will still go bare in a season if the birds never move off it, and bare ground next to a coop is where parasite load builds. If you cannot give more space, give the same space in two halves and alternate — the resting half regrows and the worm burden drops with it.

The app watches the pen for you. Record a pen's area and Farm Planner knows when the batch in it will outgrow the space, and raises the job while there is still time to build. Free while in early access. Create your free account

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