Last updated: 2026-06-21

Chicken Coop Size

A chicken coop size calculator helps you plan housing for a backyard flock. Enter how many birds you keep and their size class, and it returns the indoor coop floor area, the outdoor run area, the total footprint, and the number of nesting boxes to build. It is a starting point for anyone designing a coop, expanding a flock, or checking whether an existing setup gives the birds enough room.

How much space chickens need

Hens need two kinds of space: a sheltered coop where they roost and shelter at night, and a run where they spend the day. Crowding causes stress, feather-pecking, and disease, so each is sized per bird:

where $n$ is the number of birds, $s_c$ the coop space per bird, and $s_r$ the run space per bird. For standard laying hens that is about 0.37 m² of coop and 0.93 m² of run each; bantams need less and large breeds need more. Nesting boxes are sized separately, at about one box per three to four hens, since hens share and often prefer the same box.

Worked example

For six standard hens:

So plan a coop of about 2.2 m² and a run of roughly 5.6 m², for a total footprint near 7.8 m², with two nesting boxes. The fifth and sixth hens share those two boxes happily.

Reading the result

These figures assume birds that range in the run during the day; a flock confined full-time needs more space to stay healthy. Ventilation, roost length, and shade matter alongside floor area, and a coop much larger than the flock can be hard to keep warm in a cold climate. Many areas also regulate backyard poultry — flock limits, boundary setbacks, and rooster rules — so check local bylaws before building. For feeding the flock, see Dog Food Portion Calculator, and Fence Calculator for enclosing the run.