About the Chicken Coop Size Calculator
This chicken coop size calculator works out how much space your flock needs. Enter the number of birds, choose bantam, standard or large breeds and say how they will live — coop plus run, free-ranging during the day, or kept indoors full time — and it returns the indoor coop floor area, the outdoor run area, the total roost bar length, the number of nest boxes and a practical example footprint for each.
It is aimed at backyard keepers planning a first coop, people buying a prefab coop online (many are rated for far more birds than they comfortably hold), and anyone adding birds to an existing flock. Cramped chickens are more likely to peck each other, get sick and stop laying, so building with a little extra space is money well spent.
The figures are widely used backyard rules of thumb: about 4 sq ft of coop and 10 sq ft of run per standard bird, half that inside for bantams, and more for heavy breeds. Birds that spend long winters shut in, or that never go outside, need the larger indoor allowance. Check local rules on keeping poultry, flock size limits and setbacks before you build.
With the default inputs, the coop floor area is 24 sq ft. Change any value above to recalculate instantly.
How to use the chicken coop size calculator
- 1Enter how many chickens you have or plan to keep.
- 2Choose the breed size — bantam, standard or large.
- 3Pick how they will live: with a run, free-ranging or indoors only.
- 4Read the coop and run area, roost length and nest boxes.
- 5Use the example footprint to plan or compare prefab coops.
Formula and method
Space per bird depends on size. The calculator uses common backyard guidance: bantams 2 sq ft of coop and 5 sq ft of run, standard breeds 4 sq ft and 10 sq ft, and large or heavy breeds 5 sq ft and 15 sq ft. If the birds free-range by day, no run is added; if they never go outside, the coop itself must provide the larger outdoor allowance (5, 10 or 15 sq ft per bird).
Roost length allows 6 inches of perch per bantam, 10 inches per standard bird and 12 inches per large bird, converted to feet. One nest box per four hens is enough because hens share boxes, rounded up with a minimum of one. The example footprints pick a convenient width (4, 6 or 8 ft for coops; 6, 8 or 10 ft for runs) and round the length up to whole feet.
- birds
- Number of chickens in the flock
- sq ft per bird
- Space allowance for the breed size and housing style
- ⌈ ⌉
- Round up to the next whole number
Worked examples
6 standard hens with a run
Six standard hens need 6 × 4 = 24 sq ft of coop (a 4 × 6 ft coop) and 6 × 10 = 60 sq ft of run (6 × 10 ft). Ten inches of perch each gives 5 ft of roost, and two nest boxes are enough.
10 bantams with a run
Bantams need half the space: 10 × 2 = 20 sq ft of coop and 10 × 5 = 50 sq ft of run. Six inches of perch each makes 5 ft of roost, and 10 ÷ 4 rounds up to 3 nest boxes.
12 large-breed hens that free-range
Twelve Brahma-sized hens need 12 × 5 = 60 sq ft of coop. Because they free-range by day, no run is counted. They need 12 ft of roost (12 in each) and three nest boxes; an 8 × 8 ft coop works.
8 standard hens kept indoors
Birds that never go outside need the full 10 sq ft each indoors, so eight hens need 80 sq ft — for example an 8 × 10 ft shed — plus 6.7 ft of roost and two nest boxes.
Frequently asked questions
How many square feet does a chicken need?+
A common rule is about 4 sq ft of indoor coop space and 10 sq ft of outdoor run per standard-size chicken. Bantams can manage with about 2 sq ft inside and 5 sq ft outside, while heavy breeds such as Brahmas need more.
How big should a coop be for 6 chickens?+
For six standard hens, plan on at least 24 sq ft of coop (for example 4 × 6 ft) and 60 sq ft of run, plus about 5 ft of roost bar and two nest boxes. Add more space if they will be shut in for long periods.
How many nest boxes do chickens need?+
About one nest box for every four or five hens is enough, because hens happily take turns. Boxes around 12 × 12 inches suit most standard breeds; large breeds need about 14 × 14 inches.
How much roost space do chickens need?+
Allow roughly 8–10 inches of perch per standard bird, about 6 inches per bantam and 12 inches per large breed. Roosts should be higher than the nest boxes, and bars about 2–4 inches wide let birds cover their toes in cold weather.
Are prefab chicken coops big enough?+
Often not. Many small prefab coops advertise capacities based on about 1–2 sq ft per bird. Measure the floor area and divide by 4 sq ft (standard hens) to see how many birds it really suits.