Chicken Coop Size Calculator
Plan a coop and run that keeps your backyard flock healthy. Enter how many chickens you have, pick the breed size and your climate, and get the coop floor area and dimensions, run size, roost length, nest boxes, ventilation and pop door — plus daily feed and water, by-flock-size and by-breed tables, and a downloadable PDF.
| Birds | Coop | Run | Nests / roost |
|---|---|---|---|
| Enter a flock to compare | |||
| Breed size | Coop | Run | Roost / nest box |
|---|---|---|---|
| Enter a flock to compare | |||
How to use the chicken coop size calculator
Four quick steps turn your flock size into coop and run dimensions, roost length, nest boxes, ventilation and daily feed and water — with by-flock-size and by-breed tables, a chart and a downloadable report.
Describe your flock
Enter how many chickens you have, pick bantam, standard or large breeds, and add room to grow if you like.
Pick climate & outdoor time
Choose hot, mild or cold winters, and whether birds live in the run full-time or free-range most days.
Set the widths you’ll build
Enter the coop width and run width — the calculator works out the length of each.
Read results & save a PDF
Get coop and run sizes, roost, nests, vents, door, bedding, feed and water — then download a report.
How coop size is calculated
Every number starts from the space each bird needs, based on common extension-service and backyard-flock guidelines. Here is the exact math the calculator runs.
Worked example — 6 standard hens, mild climate, run full-time, 4 ft coop width, 6 ft run width
Coop: 6 × 4 sq ft = 24 sq ft → 24 ÷ 4 = 4 × 6 ft · Run: 6 × 10 sq ft = 60 sq ft → 60 ÷ 6 = 6 × 10 ft (32 ft of fence)
Roost: 6 × 10 in ÷ 12 = 5 ft · Nests: 6 ÷ 4 → 2 boxes, 12 × 12 in · Vents: 24 ÷ 10 = 2.4 sq ft
Bedding: 24 × 5 ÷ 12 = 10 cu ft · Feed: 6 × 0.25 = 1.5 lb/day (45 lb/mo) · Water: 6 × 0.125 = 0.75 gal/day
≈ a 4 × 6 ft coop with a 6 × 10 ft run, 2 nest boxes, 5 ft of roost and 2.4 sq ft of vents.
Chicken coop size charts
Handy lookups for coop and run size by flock, how breed size changes the space, and what your climate adds.
| Birds | Coop | Run | Nests / roost |
|---|---|---|---|
| 3 birds | 12 sq ft · 4×4 | 30 sq ft · 6×6 | 1 · 2.5 ft |
| 4 birds | 16 sq ft · 4×4 | 40 sq ft · 6×7 | 1 · 3.5 ft |
| 6 birds | 24 sq ft · 4×6 | 60 sq ft · 6×10 | 2 · 5 ft |
| 8 birds | 32 sq ft · 4×8 | 80 sq ft · 6×14 | 2 · 6.5 ft |
| 10 birds | 40 sq ft · 4×10 | 100 sq ft · 6×17 | 3 · 8.5 ft |
| 12 birds | 48 sq ft · 4×12 | 120 sq ft · 6×20 | 3 · 10 ft |
| 15 birds | 60 sq ft · 4×15 | 150 sq ft · 6×25 | 4 · 12.5 ft |
| 20 birds | 80 sq ft · 4×20 | 200 sq ft · 6×34 | 5 · 16.5 ft |
Lengths round up to the next whole foot. For bigger flocks, a wider walk-in coop (6–8 ft) keeps the length practical.
| Breed size | Coop | Run | Roost / nest box / pop door |
|---|---|---|---|
| Bantam (Silkie, Sebright) | 12 sq ft | 30 sq ft | 4 ft · 10×10 in · 10×12 in |
| Standard (RIR, Orpington) | 24 sq ft | 60 sq ft | 5 ft · 12×12 in · 12×14 in |
| Large (Brahma, Jersey Giant) | 36 sq ft | 90 sq ft | 6 ft · 14×14 in · 14×16 in |
Per bird: bantams need 2 sq ft inside and 5 outside, standard 4 and 10, large 6 and 15.
| Climate | Adjustment | Coop | Ventilation |
|---|---|---|---|
| Hot / humid | Vents doubled | 24 sq ft · 4×6 | 4.8 sq ft |
| Mild | Standard | 24 sq ft · 4×6 | 2.4 sq ft |
| Cold winters | +25% coop space | 30 sq ft · 4×8 | 3.0 sq ft |
Place vents up high, above the roost, so fresh air moves without a draft on sleeping birds.
What the chicken coop calculator gives you
Your flock size becomes a full build plan — inside space, outside space and the fittings that go in them.
Coop sizing at a glance
Who uses a chicken coop size calculator
Whether you’re starting with a few hens or growing a flock, the same calculator sizes the coop and run.
Getting a few backyard hens and wants to know how big a coop and run to build or buy.
- Enter 3–6 birds
- Add +25% for growth
- Check local hen limits
Designing a coop around 4×8 plywood and hardware cloth rolls and needs exact dimensions and fittings.
- Set a 4 ft coop width
- Match run to fence rolls
- Plan vents and roosts
Expanding to a dozen or more birds and planning a walk-in coop, plus monthly feed and water.
- Use a 6–8 ft width
- Pick your climate
- Budget feed by the bag
Tips for building a better coop
Space is the start — these habits keep your flock safe, healthy and laying.
Chicken coop size calculator FAQ
Quick answers about coop and run size, nest boxes, roosts, ventilation and how much your flock eats and drinks.
Six standard-size hens need about 4 sq ft each inside, so 24 sq ft of coop floor — a 4 × 6 ft coop works well.
They also need about 10 sq ft each outside, so a 60 sq ft run such as 6 × 10 ft if they’re in the run full-time.
Plan about 2 sq ft of coop and 5 sq ft of run per bantam, 4 sq ft of coop and 10 sq ft of run per standard hen, and 6 sq ft of coop and 15 sq ft of run per large breed like a Brahma.
Add 25% more coop space in cold-winter areas, where birds spend snowy days inside.
Plan one nest box for every 4 hens, rounded up. Six hens need 2 boxes and 10 hens need 3.
Use 10 × 10 inch boxes for bantams, 12 × 12 inch for standard breeds and 14 × 14 inch for large breeds.
Allow about 8 inches of roost per bantam, 10 inches per standard hen and 12 inches per large bird. Six standard hens need about 5 ft of roost bar.
Set roosts higher than the nest boxes. If the roost is longer than the coop, split it into parallel bars about 12 inches apart.
Plan 1 sq ft of ventilation for every 10 sq ft of coop floor, or 1 sq ft per 5 sq ft in hot, humid climates. A 24 sq ft coop needs about 2.4 sq ft of vents, or 4.8 sq ft in hot areas.
Put vents up high, above the roost, so moisture and ammonia escape without a draft on the birds.
Yes. In areas with cold, snowy winters, birds spend more days inside, so the calculator adds 25% more coop floor space.
Six standard hens go from 24 sq ft to 30 sq ft, which means a 4 × 8 ft coop instead of 4 × 6 ft.
If your birds roam the yard most days, a run about half the full size is enough for mornings, bad weather and when you’re away.
For 6 standard hens that’s about 30 sq ft, such as a 6 × 6 ft run, instead of 60 sq ft.
A standard hen eats about 1/4 lb of feed and drinks about 1/8 gallon of water a day. Six hens need about 1.5 lb of feed a day — 45 lb a month, roughly one 50 lb bag.
They drink about 0.75 gallons a day, and about twice that in summer heat.
Planning guide only — check your local rules. This calculator works in US units (feet, square feet, inches) and uses common extension-service and backyard-flock guidelines. Many US cities and HOAs limit the number of hens, ban roosters and set coop setbacks from property lines, so check your local ordinance before you build. Use 1/2-inch hardware cloth, not chicken wire, to keep predators out, and adjust space for your birds’ behavior and health.