Before You Order Chicks, Measure 8 Square Feet Per Hen

Measure the run and the coop separately in square feet, then divide: 8 square feet of run per standard-size hen, 2 to 3 square feet of coop floor per bird, and the two figures never stand in for each other. That division produces a bird count before you have looked at a single breed page, and the count is what should narrow your list — not a hatchery photograph, and not a minimum order somebody else picked.

The tape measure hangs on a nail inside the coop door with a stub of chalk beside it. Take both out and stand at a corner post of the run before you open anything on your phone. Walk the fence line once, then measure it, because pacing lies and it lies worst on a slope. Width and length, written down somewhere you won't lose them.

Eight by sixteen is 128 square feet. That was my first run. I divided by eight and bought for sixteen birds without subtracting the footprint of the feeder and the waterer, the arc the gate swung through, or the three feet at the low end that sat under water from November to March. By the second fall the ground under the pop door was bare and polished, and the grass was gone in a ring I could trace with my boot. The arithmetic had been fine. My number was still wrong.

Coop Floor and Run Floor Are Two Different Measurements

People blend these because both get called "space per bird," and the blend is how you end up with a coop sized like a run and a run sized like a coop.

The coop is the house — walls, roof, the place birds sleep and lay. Measure the floor wall to wall, inside the framing. The area under the roosts counts. The floor beneath a bank of nest boxes counts. A bird standing under the nests is still standing on coop floor, and if you leave that strip out you'll build the house too small and find out in January. Two to three square feet per standard bird is the working range, and I land at three when the flock is heavy breeds or the run is tight.

The run is everything outside the door, and that's where the eight square feet lives. Eight is the daytime figure. It is not a bonus tacked onto the coop number and it is not tradable. A nine-square-foot coop with a four-square-foot run is a coop with a mud apron, no matter how the two numbers look on a notepad.

Start With the Rectangle You Actually Have

Length times width. For a plain rectangle, that's the whole job.

When the corner is L-shaped

Drop a chalk line across the notch and you have two rectangles. Add them.

Say the run goes 20 feet along the back fence and 12 feet along the garage, but the last 6 feet of the 12 is taken up by the shed. That's a 20 by 6 strip and a 14 by 6 strip: 120 plus 84, or 204 square feet.

You can also measure the bounding rectangle and subtract the bite. Twenty by twelve is 240, the shed notch is six by six, so 36, and 240 minus 36 lands on 204 again. Same number. Do it both ways once anyway, because the two-way check catches a tape slip you would otherwise carry all the way to a hatchery order.

The discount almost nobody takes

Birds don't work a rectangle the way a mower does. They work the feeder, the waterer, the dust spot, the shade line, and whichever fence they can see through. The middle of a generous run often sits untouched while the edges get hammered.

So before dividing, take off the parts that aren't really available. I knock off about eighteen inches along any solid wall or fence, the strip under the eave where rain comes off the roof, the arc the gate needs, and anything that stays wet through winter. On my first run that discount came to nearly twenty square feet — a bird and a half I had been counting as space.

What survives is your operating area. Divide that by eight.

What Changes When the Birds Range Part of the Day

If the pop door opens at dawn and the flock spends the day in a fenced yard or on pasture, the eight becomes a bad-weather number rather than a daily one. On the days they're out, the run is a hallway.

On the days they aren't — a foot of snow, a hawk working the field, a week of rain — the eight comes right back, and those are the days that do the wearing. So ranging doesn't let you shrink the run. It lets you hold at eight instead of ten or twelve. A run that never gets a break from the flock wants ten to twelve square feet per standard hen, and it wants a roof over part of it.

Bantams Aren't Simply Smaller Chickens

A bantam runs a third to half the weight of a standard hen, and the figure used most often for them is four to five square feet of run. That's a fair starting place. It is not a license to halve your standard count and call the arithmetic done.

Two things don't scale. The hardware stays standard-sized — pop door height, roost height, nest box opening, feeder lip — none of it shrinks because the bird did. And a bantam in a flock of standards doesn't need half a flight zone, she needs a whole one, because the bird she's stepping around outweighs her two to one. A mixed flock wants more slack than a single-size flock, not less.

All bantams, sized for bantams, scales down honestly. Mixed, size off the standards and then add bantams until the ground pushes back.

The Ground Is the Arithmetic, Run Backward

You can skip the tape and read the dirt, because the dirt is the same calculation done in reverse.

Bare dirt in a bird-wide band under the pop door and along one fence line is traffic, and traffic is normal. Bare dirt across the whole run — a sealed, packed surface with nothing left to scratch, droppings concentrated in a ring instead of scattered across the width — means you're at the limit or past it. Grass gone in a circle around the feeder, a worn path from the door to the far corner, feathers ground into the dirt at one spot in enough quantity that you notice them without kneeling: same message, three different tellings.

It shows on the birds too. Even wear across backs and shoulders, a pattern rather than one hen, is crowding expressed on the animal instead of on the ground.

When a run turns to hardpan, adding bedding forever doesn't fix it. Either the count comes down or the ground goes up.

Vertical Space in a Narrow Run

A four-foot-wide side-yard run is where the floor math turns ugly and the third dimension starts earning its keep.

Inside the coop, the old figure is eight to ten inches of roost per standard bird, and that's usable length — a board end a bird can't land on doesn't count. If the whole flock sleeps in a heap against one wall, the problem is roost arrangement, not coop size.

Out in the run, perches at knee height, a stump or two, a bench with a roof over it. None of that adds square footage, and you can't subtract it from your eight. What it does is break sight lines and give the bottom bird somewhere to stand that isn't a corner. In a narrow run, a perch is the difference between a flock that uses the full thirty feet and a flock that huddles at one end.

The cheapest vertical trick of all: put the coop up on legs. The ground underneath stays shaded and dry and it becomes run — often the most used square feet on the property. It counts as run area, not coop area, and it only counts if it stays dry.

The Number You Take to the Catalog

Run my first setup through it properly. Two hundred and four raw square feet. Knock off eighteen inches along two solid fence lines, the eave drip strip, the gate arc, and the wet end — call it thirty-four square feet of discount, leaving about 170 usable. Divided by eight, that's 21 standard hens as a hard ceiling.

I'd keep eighteen. Two or three birds of slack costs almost nothing in eggs and buys the option to hold a pullet an extra season instead of moving her along, or to keep a bird you didn't plan on keeping.

Then the number filters the breed list, not the other way around. Eighteen standard hens is a different list than eight. If the arithmetic says twelve, it's the wide-bodied breeds that look best in a photograph that will eat the margin first.

And plan for the adult bird in the worst month. Twenty chicks in a four-by-eight brooder look like nothing. The same twenty in that run the following November will not. Size for full-grown, in February, with the run in its February condition.

Two honest caveats. Climate moves the number: a run that drains and dries on its own carries more birds than one that stands in water half the year, at identical dimensions. Ground cover moves it again — a run with established sod behaves differently from one that was scraped to bare dirt the day the fence went up.

What stays fixed is the order of operations. Measure. Subtract what isn't usable. Divide by eight. Then, and only then, look at breeds.