Chicken Coop Size Calculator finds coop floor, run area, roost bars and nest boxes for standard, bantam and large-breed chickens, or how many birds can fit a coop you already have.
Count each bird size and pick where the flock spends the day.
Large Breeds, Roosts & Nests
Coop & Run Floor Plan
Coop Size Chart by Flock Size
| Standard Chickens | Coop Floor | Build Size | Run | Roost Bar | Nest Boxes |
|---|---|---|---|---|---|
| 2 | 8 sq ft | 2 × 4 ft | 20 sq ft | 20 in | 1 |
| 3 | 12 sq ft | 3 × 4 ft | 30 sq ft | 30 in | 1 |
| 4 | 16 sq ft | 4 × 4 ft | 40 sq ft | 40 in | 1 |
| 5 | 20 sq ft | 4 × 6 ft | 50 sq ft | 50 in | 2 |
| 6 | 24 sq ft | 4 × 6 ft | 60 sq ft | 60 in | 2 |
| 8 | 32 sq ft | 4 × 8 ft | 80 sq ft | 80 in | 2 |
| 10 | 40 sq ft | 6 × 8 ft | 100 sq ft | 100 in | 3 |
| 12 | 48 sq ft | 6 × 8 ft | 120 sq ft | 120 in | 3 |
| 14 | 56 sq ft | 8 × 8 ft | 140 sq ft | 140 in | 4 |
| 15 | 60 sq ft | 8 × 8 ft | 150 sq ft | 150 in | 4 |
| Your 17 | 64 sq ft | 8 × 8 ft | 160 sq ft | 170 in | 5 |
| 20 | 80 sq ft | 8 × 10 ft | 200 sq ft | 200 in | 5 |
| 25 | 100 sq ft | 10 × 10 ft | 250 sq ft | 250 in | 7 |
| 30 | 120 sq ft | 10 × 12 ft | 300 sq ft | 300 in | 8 |
| 50 | 200 sq ft | 16 × 16 ft | 500 sq ft | 500 in | 13 |
| 100 | 400 sq ft | 20 × 20 ft | 1,000 sq ft | 1,000 in | 25 |
How Many Chickens Fit Common Coops
| Inside Size | Floor | Standard, Run | Standard, Free-Range | Standard, Locked In | Bantams, Run | Large, Run |
|---|---|---|---|---|---|---|
| 2 × 4 ft | 8 sq ft | 2 | 2 | 0 | 4 | 1 |
| 4 × 4 ft | 16 sq ft | 4 | 5 | 1 | 8 | 3 |
| 4 × 6 ft | 24 sq ft | 6 | 8 | 2 | 12 | 4 |
| 4 × 8 ft | 32 sq ft | 8 | 10 | 3 | 16 | 6 |
| 6 × 8 ft | 48 sq ft | 12 | 16 | 4 | 24 | 9 |
| 8 × 8 ft | 64 sq ft | 16 | 21 | 6 | 32 | 12 |
| 8 × 10 ft | 80 sq ft | 20 | 26 | 8 | 40 | 16 |
| 8 × 12 ft | 96 sq ft | 24 | 32 | 9 | 48 | 19 |
| 10 × 10 ft | 100 sq ft | 25 | 33 | 10 | 50 | 20 |
| 10 × 12 ft | 120 sq ft | 30 | 40 | 12 | 60 | 24 |
| 12 × 12 ft | 144 sq ft | 36 | 48 | 14 | 72 | 28 |
Step-by-Step Math
- Birds planned = 15 standard + 2 bantam + 0 large = 17.
- Coop floor = 15 × 4 + 2 × 2 = 64 sq ft (with a run by day).
- Smallest common footprint covering 64 sq ft = 8 × 8 ft = 64 sq ft; vent = 64 sq ft ÷ 10 = 6.4 sq ft.
- Run = 15 × 10 + 2 × 5 = 160 sq ft; along the 8 ft wall it is 20 ft deep.
- Roost = 17 birds × 10 in = 170 in; bars stay 12 in from walls, so each holds up to 72 in → 3 roost bars of 57 in.
- Nest boxes = 17 hens ÷ 4 hens per box, rounded up = 5.
- Result: 64 sq ft Coop Floor.
How the Chicken Coop Size Calculator Works
The tool runs in two directions. "Coop & Run Size for My Flock" takes your counts of standard, bantam and large-breed birds and sizes the coop around them. "How Many Chickens Fit My Coop" starts from the inside length and width of a coop you already own or plan to buy.
Both modes ask where the flock spends the day. Birds with a fenced run use the coop for sleeping, laying and bad weather, so they need far less floor than birds locked in all day. Free-ranging flocks need the least, because the coop is mostly a night shelter.
In flock mode, the coop floor is the sum of each bird count times its space allowance, plus any growth buffer you set.
N is the number of standard, bantam and large birds, a is the floor allowance per bird for your daytime setup, and B is the "Room for Future Birds" percentage. Fit mode reverses the math and rounds down, so a partial bird never counts as room.
The minimum floor is then matched to the smallest common build size that covers it, such as 4 × 6 ft or 8 × 10 ft. From there the tool works out the run, the fence for it, roost bar layout, lumber, nest boxes, vent area and an egg estimate. A floor plan, two size charts and the full step-by-step math sit under the result cards.
Roosters go in their own field under the extra settings, counted among the birds you already entered. They still take floor and roost space, but nest boxes and the egg estimate use hens only.
Square Feet per Chicken in a Coop
The allowances below are the exact figures the chicken coop size calculator uses. Standard birds with a run get 4 sq ft each, the top of the 3 to 4 sq ft range Virginia Cooperative Extension gives for laying hens. Locked-in birds get 10 sq ft, the top of the 8 to 10 sq ft range from Oregon State University Extension for flocks with no outdoor access.
| Daytime Setup | Standard Coop, sq ft (m²) | Bantam Coop, sq ft (m²) | Large Breed Coop, sq ft (m²) | Run per Standard Bird, sq ft (m²) |
|---|---|---|---|---|
| Fenced run by day | 4 (0.37) | 2 (0.19) | 5 (0.46) | 10 (0.93) |
| Free-ranging the yard | 3 (0.28) | 1 (0.09) | 3.75 (0.35) | 10 (0.93), backup run |
| Locked in all day | 10 (0.93) | 4 (0.37) | 12.5 (1.16) | None |
Run space is 10 sq ft per standard bird, 5 sq ft per bantam and 12.5 sq ft per large bird. Virginia Tech lists 10 sq ft of run for laying hens and 5 to 8 sq ft for bantams, so the bantam figure sits at the low end of that range.
Penn State Extension prints lower minimums of 1.5 sq ft inside and 8 sq ft of run per laying hen. Treat those as the floor below which problems start, not a comfort target. Crowded birds peck each other, and a tight coop holds more moisture and ammonia.
Large breeds such as Brahmas, Orpingtons and Jersey Giants get 25% more room than standard hens. That is close to Penn State's own gap, where large chickens get a third more floor than laying hens.
Chicken Coop Size Chart by Flock Size
Each row below is what the chicken coop size calculator returns for standard hens with a run by day, 10 in of roost per bird and one nest box per four hens. The locked-in column shows how much the coop grows when the birds never go out.
| Chickens | Coop Floor, sq ft (m²) | Common Build Size | Coop if Locked In, sq ft | Run, sq ft (m²) | Roost Bar | Nest Boxes |
|---|---|---|---|---|---|---|
| 4 | 16 (1.49) | 4 × 4 ft | 40 | 40 (3.7) | 40 in | 1 |
| 6 | 24 (2.23) | 4 × 6 ft | 60 | 60 (5.6) | 60 in | 2 |
| 8 | 32 (2.97) | 4 × 8 ft | 80 | 80 (7.4) | 80 in | 2 |
| 10 | 40 (3.72) | 6 × 8 ft | 100 | 100 (9.3) | 100 in | 3 |
| 12 | 48 (4.46) | 6 × 8 ft | 120 | 120 (11.1) | 120 in | 3 |
| 14 | 56 (5.20) | 8 × 8 ft | 140 | 140 (13.0) | 140 in | 4 |
| 20 | 80 (7.43) | 8 × 10 ft | 200 | 200 (18.6) | 200 in | 5 |
| 25 | 100 (9.29) | 10 × 10 ft | 250 | 250 (23.2) | 250 in | 7 |
| 50 | 200 (18.58) | 16 × 16 ft | 500 | 500 (46.5) | 500 in | 13 |
| 100 | 400 (37.16) | 20 × 20 ft | 1,000 | 1,000 (92.9) | 1,000 in | 25 |
The build size often runs a little over the minimum. Ten hens need 40 sq ft, but the next common footprint is 6 × 8 ft at 48 sq ft, which leaves room for two more birds. The tool shows that spare room on the first result card, so you know how far the flock can grow before you outgrow the coop.
Virginia Tech's published plans line up with the chart. Its 8 × 8 ft layer house is drawn for 15 to 20 hens, and its 20 × 20 ft house for 100 to 130 hens.
How Many Chickens Fit Common Coop Sizes
Fit mode in the chicken coop size calculator answers the reverse question for a coop you already have. The counts below are rounded down from the floor area and match the chart built into the tool.
| Inside Size | Floor, sq ft (m²) | Standard, Run | Standard, Free-Range | Standard, Locked In | Bantams, Run | Large, Run |
|---|---|---|---|---|---|---|
| 2 × 4 ft | 8 (0.74) | 2 | 2 | 0 | 4 | 1 |
| 4 × 4 ft | 16 (1.49) | 4 | 5 | 1 | 8 | 3 |
| 4 × 6 ft | 24 (2.23) | 6 | 8 | 2 | 12 | 4 |
| 4 × 8 ft | 32 (2.97) | 8 | 10 | 3 | 16 | 6 |
| 6 × 8 ft | 48 (4.46) | 12 | 16 | 4 | 24 | 9 |
| 8 × 8 ft | 64 (5.95) | 16 | 21 | 6 | 32 | 12 |
| 8 × 10 ft | 80 (7.43) | 20 | 26 | 8 | 40 | 16 |
| 8 × 12 ft | 96 (8.92) | 24 | 32 | 9 | 48 | 19 |
| 10 × 10 ft | 100 (9.29) | 25 | 33 | 10 | 50 | 20 |
| 10 × 12 ft | 120 (11.15) | 30 | 40 | 12 | 60 | 24 |
| 12 × 12 ft | 144 (13.38) | 36 | 48 | 14 | 72 | 28 |
Measure inside the walls, not the outside of the frame. Studs, sheathing and a nest box bank can take several square feet out of a small coop, and that is enough to drop a 4 × 4 ft coop from four hens to three.
Fit mode also shows what the same floor holds with the other two bird sizes and under another daytime setup. If the floor is too small for even one bird, the tool says how short it is and suggests using the box as a nest or brooder instead.
Run Size and Fence Length
The second result card of the chicken coop size calculator sizes the run for your flock and places it along the long wall of the coop. The run depth is the run area divided by that wall length. Fence is needed on the three open sides, since the coop wall closes the fourth.
The same card adds the coop and run together as one footprint, which is the ground you need to clear and level. For a run that sits apart from the coop, the Rectangle Fence Perimeter Calculator gives the full four-sided length. Posts, rails and panels come from the Fence Calculator.
Predators dig at the base of a fence. Both Penn State and Virginia Tech advise burying the wire at least 12 in deep and bending it outward about 6 in, so a digging animal hits more wire. Cover the top with mesh or netting to stop hawks and owls, and use the Fence Post Depth Calculator to set the posts.
Free-range flocks still get a backup run on the card. It covers storm days, nesting season and times when a hawk is working the yard. Locked-in flocks get a different card instead, showing how much coop floor you would save by adding a run.
Roost Bars, Nest Boxes and Vents
In the chicken coop size calculator, roost length is the bird count times your roost space per bird, set to 10 in by default. Virginia Tech recommends 8 to 10 in per chicken, and Oregon State gives 5 to 10 in. Penn State allows 6 in for standard birds and 4 in for bantams, so lower the setting for a bantam flock. For heavy breeds, raise it toward the 12 in per bird that University of Kentucky Extension uses.
The tool keeps each bar 12 in from the end walls and 12 in from the next bar, in line with both Kentucky's and Penn State's one-foot spacing. It splits the total into equal bars that run along the long wall and counts 8 ft 2×4 boards laid flat. If the bars will not fit side by side, the card turns amber and suggests a ladder-style stagger.
Kentucky Extension sets roosts 16 to 40 in above the floor, the range shown on the roost card. Penn State is narrower, at 18 to 24 in for standard birds and 12 to 18 in for bantams. Keep heavy birds near the low end, since Penn State warns that perches over 4 ft high lead to leg injuries when birds jump down.
Nest boxes default to one per four hens, which you can change from 1 to 10. Oregon State uses one box per about four birds at 12 × 12 × 12 in, and Virginia Tech uses one per four or five hens. Penn State asks for two boxes for the first four hens, then one more for every four after that. The count uses hens only, so roosters entered in their own field add no boxes.
Keep the boxes lower than the roosts. Hens sleep on the highest spot they can reach, and a box above the bars fills with droppings overnight. Utah State University Extension places nests no less than 18 in off the floor.
Vent area on the first card is one-tenth of the floor, so a 64 sq ft coop gets 6.4 sq ft of opening. That is the planning ratio in Manitoba Agriculture's 2026 small-flock bulletin, with vents placed above bird height. Penn State adds that vents should never open directly over the roosts, because a draft on sleeping birds does more harm than cold air alone.
The egg rows on the fourth card assume four eggs per hen each week. Real output swings with breed, age and season. Virginia Tech notes that hens need about 14 to 16 hours of light to keep laying at a high rate.
Worked Example: 17 Birds in an 8 × 8 Coop
The chicken coop size calculator opens with 15 standard hens and 2 bantams, kept in a run by day. The coop floor is 15 × 4 + 2 × 2 = 64 sq ft. The smallest common build that covers it is 8 × 8 ft, an exact fit with no spare room, and the vent opening comes to 6.4 sq ft.
The run is 15 × 10 + 2 × 5 = 160 sq ft. Along the 8 ft wall it runs 20 ft deep, which takes 48 ft of fence for three sides. Coop and run together cover 224 sq ft of ground.
Roost length is 17 × 10 = 170 in. Each bar can be up to 72 in long once 12 in is kept clear at both ends, so the tool splits the total into three bars of 57 in, cut from three 8 ft 2×4s. Nest boxes come to 17 ÷ 4 = 4.25, rounded up to five.
The egg estimate is about 9.7 eggs a day, or roughly 24.3 dozen a month. The result fits Virginia Tech's 8 × 8 ft layer house plan, which is drawn for 15 to 20 hens.
Chicken Coop Size Calculator in Meters
Switch Result Units to Metric and every card, chart and step reports in m², m and cm. Length and width inputs in fit mode also take meters or centimeters. One sq ft is 0.0929 m², so the 4 sq ft run allowance is 0.37 m² per bird and the 10 sq ft locked-in figure is 0.93 m².
For a 1,000-chicken house, backyard figures give 4,000 sq ft (371.6 m²) of house with a run and 10,000 sq ft (929 m²) of run. The tool accepts up to 1,000 birds of each size, but it flags any flock over 100 birds. Commercial layer and broiler houses follow stocking rules set by their buyer or welfare program, so check those before you build at that scale.
Print Results opens every chart and the floor plan in one printout. Choose "Save as PDF" in the print window to keep a chicken coop size calculator PDF of your own numbers for the lumber yard.
A chicken tractor is a bottomless coop and run that you drag to fresh ground. Size it with the run setup and use the coop + run footprint as the tractor's total frame. For a hoop-style coop, the Hoop House Calculator handles hoop spacing and covering. Converting a garden shed is often cheaper than a new build, and the DIY Shed Cost Calculator or Lean To Cost Calculator will price the structure.
Chicken Coop Size Questions
The answers below use the chicken coop size calculator's standard allowances of 4 sq ft of coop and 10 sq ft of run per standard hen, unless a different setup is named.
How does the chicken coop calculator work?
In the chicken coop size calculator, pick a mode, choose where the flock spends the day, and enter bird counts or coop dimensions. The tool multiplies each bird count by its floor allowance, adds the results, and matches the total to a common build size. It then sizes the run, fence, roost bars, nest boxes and vents from that same flock and footprint.
How many square feet does a chicken need in a coop?
A standard hen needs about 4 sq ft of coop floor with a run, 3 sq ft if she free-ranges and 10 sq ft if she stays inside all day. Bantams need 2, 1 and 4 sq ft for the same setups. Large breeds need 5, 3.75 and 12.5 sq ft.
What is the ideal size for a chicken coop?
The ideal coop is the smallest common build that covers your flock's floor need, plus room for birds you will add later. Six hens with a run need 24 sq ft, so a 4 × 6 ft coop fits them exactly. Set the "Room for Future Birds" buffer to 25% and the same flock calls for 30 sq ft and a 4 × 8 ft build.
How many square feet should a chicken coop be?
Multiply your bird count by the allowance for your setup. Twelve hens with a run need 12 × 4 = 48 sq ft, which is a 6 × 8 ft coop. The same twelve locked in all day need 120 sq ft, which is a 10 × 12 ft coop.
Is a 4x8 coop big enough for 8 chickens?
Yes, if the birds have a run by day. A 4 × 8 ft coop has 32 sq ft, and 32 ÷ 4 = 8 hens. They need 80 in of roost, which fits as two 40 in bars along the 8 ft wall, plus two nest boxes and an 80 sq ft run. Locked in all day, the same coop holds only three.
How many chickens can fit in a 10x10 coop?
A 10 × 10 ft coop has 100 sq ft, enough for 25 standard hens with a run or 33 that free-range. It holds 10 hens locked in all day, 50 bantams with a run or 20 large-breed birds. Twenty-five hens also need a 250 sq ft run.
Is a 4x4 coop big enough for 4 chickens?
Yes, with a run. Four hens need 16 sq ft, which is exactly what a 4 × 4 ft coop gives, so there is no spare room for a fifth bird. Their 40 in of roost fits as two 20 in bars. Without a run, a 4 × 4 ft coop suits only one hen.
Is a 2x4 coop big enough for chickens?
A 2 × 4 ft coop has 8 sq ft. That holds two standard hens or four bantams with a run, and no birds kept inside all day. Chickens are flock birds and most keepers start with at least three, so a 2 × 4 ft coop works best for bantams.
How many chickens can sleep in an 8x12 coop?
Floor space allows 24 standard hens with a run. They need 240 in of roost, which fits as two 120 in bars along the 12 ft wall with plenty of width to spare. At Penn State's tighter 6 in per bird those two bars could seat 40, but the floor is the real limit.
How many chickens can sleep in a 10x12 coop?
A 10 × 12 ft coop has 120 sq ft, enough for 30 standard hens with a run. Their 300 in of roost splits into three bars of 100 in each, spaced a foot apart. Locked in all day, the same coop holds 12 hens.
What size of a chicken coop is for 10 chickens?
Ten hens need 40 sq ft with a run, so a 6 × 8 ft coop fits them with room for two more. Free-ranging hens need 30 sq ft, which a 4 × 8 ft coop covers. Locked in all day they need 100 sq ft, or a 10 × 10 ft coop.
What size coop for 12 chickens?
Twelve hens with a run need 48 sq ft, an exact fit for a 6 × 8 ft coop. Plan a 120 sq ft run, 120 in of roost and three nest boxes.
What size coop do I need for 14 chickens?
Fourteen hens need 56 sq ft with a run. The next common build is 8 × 8 ft at 64 sq ft, which leaves room for two more hens. Add a 140 sq ft run, 140 in of roost and four nest boxes.
How much space do 20 chickens need in a coop?
Twenty hens need 80 sq ft of coop with a run, which is an 8 × 10 ft build. They also need a 200 sq ft run, 200 in of roost split into three bars of 67 in, and five nest boxes. Kept inside all day, they need 200 sq ft of coop instead.
How big of a coop do I need for 4 chickens?
Four hens with a run need 16 sq ft, so a 4 × 4 ft coop and a 40 sq ft run. Free-ranging hens need 12 sq ft. If they stay in the coop all day, plan 40 sq ft, which takes a 6 × 8 ft build.
How many nesting boxes do I need per chicken?
Plan one box for every four hens. Oregon State uses that ratio, and Virginia Tech allows one box for four or five. Each box should be about 12 × 12 × 12 in. Roosters do not need boxes, and the calculator leaves them out once you enter them in the Roosters field.
Can I put ducks in my chicken coop?
Yes, but ducks need more floor and handle the space differently. Virginia Tech lists 5 sq ft inside and more than 15 sq ft of run per duck, and ducks rarely use perches, so they sleep on the floor. They also splash water, so keep their waterer in the run to keep the bedding dry.
The chicken coop size calculator has no duck setting. Entering each duck as a large-breed bird gives the right 5 sq ft of coop floor. Add a 20% buffer to bring the run closer to the 15 sq ft per duck that Virginia Tech suggests.
Can I have 5 hens and 1 rooster?
Yes, and a rooster takes the same floor and roost space as a hen. Enter 6 standard chickens and 1 in the Roosters field. The tool sizes a 24 sq ft coop, a 60 sq ft run and 60 in of roost for all six birds.
Nest boxes and eggs use the five hens only, which gives 5 ÷ 4 rounded up to 2 boxes and about 2.9 eggs a day. Check your local ordinance before you add a rooster.
What is the 90/10 rule for chickens?
The 90/10 rule means at least 90% of what a hen eats should be complete layer feed, with treats and scraps kept to 10% or less. VCA Animal Hospitals veterinarian Gregory Rich, DVM, sets the same 10% cap on treats from all food sources.
Kentucky Extension explains why the cap matters. Scratch grains and cracked corn dilute the nutrients in layer feed, so it suggests giving them only at night and only as much as the flock eats in 15 minutes. Penn State also suggests at least 3 in of feeder space per bird, so low-ranking hens can still reach the feed.
What is the biggest killer of chickens?
Predators and disease are the two big threats a coop has to handle. Virginia Tech notes that most predation happens at night, which is why a locked coop and a covered run matter so much. Its authors also advise keeping wild birds away from the flock to cut the risk of avian influenza.
How do I find a coop and run size?
Count your birds by size, then multiply each count by its coop and run allowance. Eight standard hens and four bantams with a run need 8 × 4 + 4 × 2 = 40 sq ft of coop. Their run is 8 × 10 + 4 × 5 = 100 sq ft. The tool does this sum and also turns it into a build size and fence length.
Should I buy a bigger chicken coop?
Usually yes, within reason. Most flocks grow, and a coop sized to the exact minimum leaves no room for new chicks. Set the "Room for Future Birds" buffer in the chicken coop size calculator to see the next size up. Do not oversize by a wide margin for a small flock, though, because a few hens in a large, open coop lose body heat on winter nights.