Home › Home & Construction › Chicken Coop Calculator
Chicken Coop Calculator
Use this free chicken coop calculator to size a coop and run for your flock before you buy lumber or order a kit. Enter how many hens you keep and their breed size, and the calculator works out the indoor coop area, the outdoor run area, how many nesting boxes you need, the roost length, and how many feeders and waterers to provide.
Defaults follow the breed you pick: 2 and 8 for bantams, 4 and 10 for standard hens, 5 and 12 for large breeds. Raise them if your flock stays shut in for long winters.
| Amount | Value |
|---|---|
| Coop floor area | 32 sq ft |
| Suggested coop size | 4 ft × 8 ft |
| Run area | 80 sq ft |
| Suggested run size | 8 ft × 10 ft |
| Nesting boxes (1 per 4 hens) | 2 |
| Roost length | 6.7 ft (80 in) |
| Feeders (1 per 10 hens) | 1 |
| Waterers (1 per 8 hens) | 1 |
How it works
A coop is really two spaces: the indoor coop where hens sleep and lay, and the outdoor run where they spend the day. Both are sized by multiplying the number of hens by a per-bird allowance, and the allowances depend on breed size. A standard hen, such as a Rhode Island Red or a Leghorn, needs 4 square feet indoors and 10 square feet in the run. A bantam, roughly a third the size, needs 2 square feet indoors and 8 in the run. A large heavy breed, such as an Orpington or a Brahma, needs 5 square feet indoors and 12 in the run.
The calculator lets you change those allowances, because they are minimums, not ideals. If your flock is shut inside for a long winter, or if you keep an active breed that paces the fence, give them more room. Crowded birds peck each other, lay fewer eggs, and spread disease faster. The suggested coop size is a practical rectangle for the area: a 32 square foot coop becomes 4 by 8 feet, which suits standard sheet lumber with little waste, and an 80 square foot run becomes 8 by 10 feet.
Run area = hens × run sq ft per bird
Nesting boxes = hens ÷ 4, rounded up
Roost length = hens × 10 inches (standard), 8 inches (bantam), 12 inches (large)
Feeders = hens ÷ 10, rounded up · Waterers = hens ÷ 8, rounded up
Nesting boxes follow a simple rule: one box for every four hens, rounded up. Eight hens need two boxes and twelve need three. Hens share happily and will often queue for the same favorite box, so extra boxes rarely help. Each box should be about 12 inches square, dark, dry, and lined with clean straw or shavings, and it should sit lower than the roosts, or the birds will sleep in the boxes and soil them.
Roost length is 10 inches per standard hen, 8 inches per bantam, and 12 inches per large bird. Roosts belong at least 18 inches off the floor, and higher than the nesting boxes, because chickens sleep at the highest point they can reach. A 2 by 4 board laid flat, wide side up, makes a good roost: on cold nights the birds settle down and cover their feet with their bodies.
Feeders and waterers are sized the same way: one feeder per 10 hens and one waterer per 8 hens, rounded up. A flock of eight needs one of each; a flock of twenty needs two feeders and three waterers. Keep them in the run during the day, raise them to the height of a hen's back so bedding stays out, and check the water daily. A hen drinks about a pint of water a day, and twice that in hot weather.
Worked example
You keep 8 standard hens and want to know how big a coop and run to build.
Step 1: Coop area — 8 hens × 4 sq ft per bird = 32 sq ft, which fits a 4 ft × 8 ft coop.
Step 2: Run area — 8 hens × 10 sq ft per bird = 80 sq ft, which fits an 8 ft × 10 ft run.
Step 3: Nesting boxes — 8 ÷ 4 = 2 boxes.
Step 4: Roost length — 8 × 10 inches = 80 inches, or 6.7 ft.
Step 5: Feeders and waterers — 8 ÷ 10 rounds up to 1 feeder, and 8 ÷ 8 = 1 waterer.
The result is a 32 sq ft coop and an 80 sq ft run for 8 standard hens, with 2 nesting boxes, 6.7 ft of roost, 1 feeder, and 1 waterer.
FAQ
How much space does each chicken need in a coop?
A standard-size hen needs about 4 square feet of indoor coop space, a large heavy breed needs about 5 square feet, and a bantam needs about 2 square feet. These are minimums for birds that also have an outdoor run. If your flock stays shut inside all winter, give them more room, because crowded birds peck each other, lay fewer eggs, and get sick more easily.
How big should the run be?
Plan on about 10 square feet of run per standard hen, 12 square feet for a large heavy breed, and 8 square feet for a bantam. The run is where chickens scratch, dust bathe, and stretch their legs, so a bigger run always beats a bigger coop if you have to choose. A run that is too small turns to bare dirt and mud quickly, and the birds get bored and start feather pecking.
How many nesting boxes do I need?
One nesting box for every four hens is the standard rule. Eight hens need two boxes, twelve hens need three, and twenty hens need five. Hens are happy to share and will often queue for the same favorite box, so adding more boxes than the rule calls for rarely helps. Each box should be about 12 inches square, dark, and lined with clean straw or shavings.
How much roost space does each chicken need?
Allow about 10 inches of roost bar per standard hen, 12 inches for a large breed, and 8 inches for a bantam. Roosts should sit at least 18 inches off the floor and higher than the nesting boxes, because chickens like to sleep at the highest point they can reach. A 2 by 4 board laid flat, wide side up, makes a good roost: the birds can cover their feet with their bodies on cold nights.
Do chickens need a feeder and waterer inside the coop?
One feeder serves about 10 hens and one waterer serves about 8 hens, so a small backyard flock usually needs one of each. Keep the feeder and waterer in the run during the day and inside the coop only if the flock is shut in. Raise them to the height of a hen's back to keep bedding and droppings out, and check the water daily: a hen drinks about a pint of water a day, and twice that in hot weather.