Chicken Coop Size Calculator

How it is calculated

Each space is the flock size multiplied by an allowance per bird: coop = birds × coop ft², run = birds × run ft², roost = birds × roost ft, and total = coop + run. Areas are in square feet and the roost bar is in linear feet; the tool does not convert units, so metric figures must be converted first. Nesting boxes follow a fixed rule built into the tool: boxes = ceil(birds ÷ 4), never fewer than one, so every started group of four hens adds a box. The number of birds must be a whole number of at least 1, so 7.5 birds gives no result, and all three allowances must be positive. The defaults (4 ft², 10 ft², 0.75 ft) are starting points; larger breeds, bantams or a smaller run need different allowances.

Common mistakes

• Entering allowances in square metres or metres: the fields are square feet and feet, so 4 m² per bird would be read as 4 ft² and the coop would come out far too small.
• Adding coop and run area together and calling that the coop floor; the total is the whole footprint, while only the coop figure is the enclosed, roofed floor.
• Sizing for today's count only: with 7 hens you get 2 nesting boxes, but adding two chicks pushes it to 3 boxes and 8 ft² more coop floor.
• Treating the roost figure as the length of one perch; it is the combined bar length for all birds, which you can split across several bars at different heights.
• Entering a fractional flock such as 7.5 birds or a zero or negative allowance. These give no result rather than a rounded answer.