Nesting Box & Roost Calculator
Nesting Box & Roost Calculator
The two fittings every coop needs, sized in seconds: nesting boxes at one per four hens, and the full roost length your flock will claim every night.
Hens happily share nests: one box per four hens is the standard allowance, and more boxes mostly means more empty boxes — the whole flock often queues for one favourite. Roost space is the opposite: every bird needs her own 10 inches on the bar, every night.
Quick reference
Your coop fittings
Each box is about 12 × 12 inches (30 × 30 cm) — big enough for one hen to turn around in. Roosts should sit higher than the boxes, or hens will sleep (and dirty) in the nests instead.
How it works
Two standard allowances do all the work: nesting boxes = hens ÷ 4 (rounded up, minimum one), and roost length = hens × 10 inches. A row of boxes takes about a foot of wall per box, since each box is roughly 12 inches wide.
Worked example: 12 hens need 3 nesting boxes and 10 ft of roost (120 inches, about 3.05 m) — usually built as two 5 ft bars or one long bar with a mid support. If your coop plan gives you only 8 ft of roost wall, the maths is telling you the coop honestly fits about 9–10 hens at roosting time, whatever the floor area says.
Nesting boxes & roost by flock size
For common flock sizes — boxes at 1 per 4 hens, roost at 10 inches per bird.
| Hens | Nesting boxes | Roost length | Roost (m) | Box row width |
|---|---|---|---|---|
| 4 hens | 1 box | 3.3 ft | 1 m | about 1 ft |
| 6 hens | 2 boxes | 5 ft | 1.5 m | about 2 ft |
| 8 hens | 2 boxes | 6.7 ft | 2 m | about 2 ft |
| 10 hens | 3 boxes | 8.3 ft | 2.5 m | about 3 ft |
| 12 hens | 3 boxes | 10 ft | 3 m | about 3 ft |
| 16 hens | 4 boxes | 13.3 ft | 4.1 m | about 4 ft |
| 20 hens | 5 boxes | 16.7 ft | 5.1 m | about 5 ft |
| 24 hens | 6 boxes | 20 ft | 6.1 m | about 6 ft |
| 30 hens | 8 boxes | 25 ft | 7.6 m | about 8 ft |
Frequently asked questions
How many nesting boxes do I need per chicken?
One box per four hens is the standard allowance, with a minimum of one box even for a tiny flock. Hens share happily and lay mostly in the morning, so 12 hens genuinely need only 3 boxes — adding more mostly gives you more empty boxes while the flock queues for a favourite.
How big should a nesting box be?
About 12 × 12 × 12 inches (30 cm cube) suits most standard breeds; go a couple of inches larger for heavy breeds like Orpingtons. Bigger is not better — an oversized box invites two hens to squeeze in together, which is how eggs get broken.
How much roost space does a chicken need?
Plan 10 inches (25 cm) of roost bar per standard bird — 8 inches is the tight minimum and bantams need a little less. In summer hens spread out and use every inch; in winter they huddle and use half of it, but size for summer so nobody gets pushed off the end.
Should roosts be higher than the nesting boxes?
Yes. Chickens instinctively sleep at the highest comfortable point, so if the boxes are higher than the roosts, hens will sleep in the boxes — and dirty them overnight. Put roosts above box height and both problems disappear.
What is the best shape for a roost bar?
A wide, flat-ish perch suits chicken feet best — a 2×4 laid flat (wide side up) or a rounded-corner plank about 2–4 inches wide lets them sit with toes flat and covered by feathers in winter, which prevents frostbitten toes. Thin round poles are the least comfortable option.