A dozen hens need 48 sq ft of coop floor and 96 to 120 sq ft of run, and two of our plans fit it without crowding: the 8x10 walk-in (66 sq ft floor, 96 sq ft run, rated 12-14) and the 8x12 chicken coop (80 sq ft, 96 sq ft run, rated 12-19). The 6x10 walk-in (47 sq ft, rated 9-12) also carries twelve, but at its ceiling. The 8x12 walk-in with feed room (58 sq ft, 128 sq ft run, rated 14-18) is the overbuild if twelve is going to become sixteen.
Twelve is the first flock size where you stop thinking about a box you reach into and start thinking about a shed you walk into. Both of the main picks on this page are classed walk-in in our plan data and share a 34 by 52 inch door: the 8x10 on 76-inch walls at ground level, the 8x12 coop on 64-3/4 inch walls raised 24 inches off the ground. At a dozen birds the daily scrape is long enough that standing up matters, and the walk-in plans guide covers the whole family.
The four plans at twelve hens
| Plan | Coop floor | Run | Rated | Coop per hen at 12 | Run per hen at 12 | Nests | Roost bars built | Walls | Materials | Build |
|---|---|---|---|---|---|---|---|---|---|---|
| 8x10 walk-in | 66 sq ft | 96 sq ft | 12-14 | 5.5 | 8.0 | 4 | 146 in | 76” | $3,700-$4,750 | 46-58 hrs |
| 8x12 chicken coop | 80 sq ft | 96 sq ft | 12-19 | 6.7 | 8.0 | 5 | 219 in | 64-3/4” + 24” floor clearance | $3,950-$5,050 | 55-70 hrs |
| 6x10 walk-in | 47 sq ft | 72 sq ft | 9-12 | 3.9 | 6.0 | 3 | 147 in | 72” | $3,200-$4,100 | 36-44 hrs |
| 8x12 walk-in + feed room | 58 sq ft | 128 sq ft | 14-18 | 4.8 | 10.7 | 5 | 219 in | 76” | $4,250-$5,450 | 60-75 hrs |
Twelve hens want 96 to 120 inches of roost and three nest boxes (Oregon State’s one per four) or four (Penn State’s two-for-the-first-four rule). The 8x10 has exactly four boxes and a 140-inch roost allowance (10 per hen at its 14-bird top; the cut list builds two 73-inch bars, 146 inches), which is why it reads as the plan drawn for this number. The 8x12 coop has five boxes and three 73-inch bars, 219 inches, built for the top of its 19-bird rating.
8x10 or 8x12
Both are 8 feet wide with a 96 sq ft run. The 8x12 chicken coop is a different animal from the 8x12 walk-in with feed room: it’s a raised coop on 24-inch floor clearance with 64-3/4 inch walls and a taller ridge (153 inches), no feed room, and the full 80 sq ft goes to the birds. That’s the most bird floor of any plan under $4,000. At twelve hens it’s 6.7 sq ft each, which is more than they need, and the rating runs to 19.
The 8x10 walk-in is a ground-level shed with 76-inch walls, 66 sq ft of floor, $250 to $300 cheaper and 9 to 12 hours quicker. At twelve it’s 5.5 sq ft a bird, still well over our 4. Its range is 12 to 14, so there’s room for two more and no more than that.
The choice is really about whether twelve is the number. If it is, the 8x10 is the right-sized coop with money left over. If the flock is going to drift up, the 8x12 coop’s 19-bird rating is the cheapest headroom in the line, and the 24-inch floor clearance gives the birds a shaded strip under the coop that doesn’t count in the run figure.
The 6x10 at its limit
Twelve is the ceiling of the 6x10 walk-in. At 3.9 sq ft a hen it’s above Oregon State’s 3 and a hair under our 4, and the 72 sq ft run is 6 per bird, a confinement number. It’s $500 cheaper than the 8x10 and fits a 7-foot-wide strip. For twelve hens that free-range daily on a narrow lot it’s fine. For twelve hens that live in the run, spend the $500.
Nest boxes at twelve
This is the flock size where the nest bank stops being an afterthought. Four boxes at 12 inches plus wide is a 59-3/4 inch bank on the 8x10, and Utah State wants it at least 18 inches off the floor with a 4 to 6 inch lip so the bedding and eggs stay in. Both 8-foot plans mount the bank on an exterior wall with an outside lid, so you collect without going in. The nesting box guide covers roll-out trays and why boxes always sit below the roost.
Cost per hen
Low-end materials: the 8x10 is $308 a hen at twelve, the 8x12 coop $329 at twelve but $208 at its rated 19, the 6x10 $267. The number worth counting is the cost of rebuilding a coop that was too small, which is what this page is trying to save you.
Every plan is free on its page, cut list and all. The $4.99 Etsy book is the printable version. If you want to check the math for a different breed mix, the size calculator takes bantams and heavy breeds into account.
