Chicken Coop Size Calculator

Enter how many birds you keep to get coop floor space, run size, roost length, nest boxes and ventilation, with example dimensions.

Do they free-range during the day?

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Chicken Coop Size Calculator · HerdMath

How it works

The common rule of thumb is 4 square feet of coop floor and 10 square feet of run per standard-size chicken. Bantams need about half that, and big breeds like Brahmas need more. If your birds are shut in the coop all day, give them extra room.

How to use it

Enter your flock size, including birds you plan to add. Most people end up with more chickens than they planned.

Reference chart

Breed sizeCoop / birdRun / birdRoost / bird
Bantam2 sq ft5 sq ft6 in
Standard4 sq ft10 sq ft8–10 in
Large breed5 sq ft15 sq ft10–12 in

Frequently asked questions

How big should a coop be for 6 chickens?

At least 24 square feet for standard breeds (for example 4 × 6 ft), with a run of about 60 square feet. Give them more if they're confined full time.

How many nest boxes do I need?

About one nest box for every 4 hens. Hens share boxes and often pick the same favorite one.

How much roost space does a chicken need?

About 8–10 inches of roost bar per standard bird, less for bantams and more for large breeds. Birds huddle closer in winter.

How much ventilation does a coop need?

A common guideline is about 1 square foot of ventilation per 10 square feet of floor. Put vents high, above the roosts, so birds aren't in a draft.

Figures are typical values from university extension and breed-association guidance. Estimates only. Individual animals vary — confirm pregnancy and health questions with your veterinarian. Last reviewed 2026-09-18.