Does this apply if I only keep a couple of hens?

The per-hen figures still apply, but for a very small flock most keepers choose a larger coop than the strict minimum suggests — even manufacturers generally size pre-made coops for practical use, not the bare legal figure.

Does giving hens a run mean I can use a smaller coop?

No — the coop floor figure stays the same either way under UK standards. A run adds extra space on top of the coop requirement rather than reducing it; coop and run are two separate space budgets.

Do rescued ex-battery hens need different space?

The British Hen Welfare Trust sets a lower run-space minimum specifically for ex-caged rescue hens (1m² per hen, versus 2m² for other hens) while they adjust — check with the rehoming organisation for their specific guidance.

Do bantam or smaller breeds need less space than the figures above?

Generally yes, proportionally, but the published standards are written for standard-size hens. If you're keeping a smaller breed, treat these figures as a safe upper bound rather than assuming a precise reduction.

Does more coop space mean I need fewer nest boxes?

No — nest box count is driven by flock size (commonly one box per five hens), not floor area. A bigger coop with too few nest boxes still causes queuing and egg-laying stress.

Can I legally keep chickens in my back garden?

In most UK residential areas, yes — chickens are the most commonly permitted backyard animal precisely because they're quiet, small and low-impact. Roosters are the main exception: a lot of restrictions target roosters specifically, for crowing noise, while happily permitting hens. Check with your local council for any flock-size cap or registration requirement.

Is there a version of this for the US?

Yes — see the US chicken coop size calculator, based on Cooperative Extension System guidance.

Chicken Calculator

How much space do your hens actually need?

Enter your flock size to get coop, perch and run space — drawn from UK welfare standards, not a guess.

🇬🇧 UK version/🇺🇸 US version

Standards usedUK legal minimumRSPCA Assured standard

Number of hens

Outdoor run access?

Coop floor space needed

0.44 m²

0.11 m² per hen × 4 hens (legal minimum / RSPCA Assured)

Feed cost calculator · Water calculator · Bedding calculator · Cost of keeping calculator

Perch space needed

60 cm

Outdoor run space

8.00 m²

2.00 m² per hen (British Hen Welfare Trust minimum; 1m²/hen for ex-caged rescue hens specifically)

What this means

A roughly square coop floor would be about 0.7m × 0.7m. Long, narrow coops work too.

If you’re building a rectangular coop, examples include: 0.7m × 0.7m, 0.5m × 0.9m, 0.4m × 1.2m.

You’ll also want 1 nest box (commonly recommended at 1 per 5 hens).

Working backwards: how many chickens fit?

Floor area you have (m²)

Coop floor space and perch figures apply to England and reflect both the Welfare of Farmed Animals (England) Regulations 2007 (non-cage systems) and RSPCA Assured's indoor standard, which specify the same stocking density for floor space — RSPCA Assured's additional welfare requirements (litter, enrichment, daily checks) aren't reflected in this figure. Run space follows British Hen Welfare Trust guidance for a garden run, not open free-range pasture. Scotland, Wales and Northern Ireland have their own regulations. This tool is a planning guide, not legal advice — check current rules before building.

How we calculated this +

Coop floor space needed

Source:: Welfare of Farmed Animals (England) Regulations 2007 (non-cage systems); RSPCA Assured laying hen standards comparison (2025)
Applies to:: England — statutory minimum and RSPCA Assured members alike
Assumption:: A maximum stocking density of 9 hens per m² of usable floor area is identical under the legal minimum and RSPCA Assured — RSPCA's welfare uplift for hens comes from litter, enrichment and perch requirements, not extra floor space, unlike the pig calculator where the two standards differ.
Calculation:: 1 ÷ 9 m² (about 0.11m²) per hen, multiplied by hen count.

Perch space needed

Source:: Welfare of Farmed Animals (England) Regulations 2007 (non-cage systems); RSPCA Assured laying hen standards comparison (2025)
Applies to:: England — statutory minimum and RSPCA Assured members alike
Assumption:: Specified identically by both the legal minimum and RSPCA Assured.
Calculation:: 15cm per hen, multiplied by hen count.

Outdoor run space

Source:: British Hen Welfare Trust, hen-setup guidance
Applies to:: A daytime garden run — a different, smaller-scale figure than open free-range pasture
Assumption:: 2m² per hen for most hens; the British Hen Welfare Trust sets a lower minimum (1m² per hen) specifically for ex-caged rescue hens while they adjust, which isn't broken out as a separate calculator result but is noted on the page.
Calculation:: 2m² per hen, multiplied by hen count, on top of coop floor space (not instead of it).

Nest boxes

Source:: Widely-recommended keeper guidance, not a legal requirement
Applies to:: England and the US alike
Assumption:: 1 nest box per 5 hens is a commonly recommended convention rather than a statutory or RSPCA Assured figure, shown as a supplementary tip rather than part of the core floor-space maths.
Calculation:: Hen count ÷ 5, rounded up.

Sources checked: September 2026.

Rules can depend on where you live. National welfare requirements aren't the same thing as local planning, registration, nuisance or disease-control rules — check with your local authority before you build or buy.

What this means

The coop floor figure — a maximum of 9 hens per m² of usable area (about 0.11m² per hen) — comes from the Welfare of Farmed Animals (England) Regulations 2007 for non-cage systems, and is identical to RSPCA Assured's own indoor standard. Unlike our pig calculator, RSPCA Assured doesn't require extra floor space over the legal minimum here — its welfare uplift for hens comes from litter, enrichment and perch requirements instead.

Perch space (15cm per hen) is specified identically by both the legal minimum and RSPCA Assured. Run space (2m² per hen) follows the British Hen Welfare Trust's minimum for a daytime garden run — deliberately a different, smaller-scale figure than open free-range pasture, since a garden run is what most backyard keepers are actually building. Coop and run are two separate space budgets: giving hens a run doesn't shrink the coop they need.

Technical methodology +

The source, assumption and arithmetic behind every figure are in “How we calculated this” above.

Sources checked: September 2026.

Common questions

Does this apply if I only keep a couple of hens?: The per-hen figures still apply, but for a very small flock most keepers choose a larger coop than the strict minimum suggests — even manufacturers generally size pre-made coops for practical use, not the bare legal figure.
Does giving hens a run mean I can use a smaller coop?: No — the coop floor figure stays the same either way under UK standards. A run adds extra space on top of the coop requirement rather than reducing it; coop and run are two separate space budgets.
Do rescued ex-battery hens need different space?: The British Hen Welfare Trust sets a lower run-space minimum specifically for ex-caged rescue hens (1m² per hen, versus 2m² for other hens) while they adjust — check with the rehoming organisation for their specific guidance.
Do bantam or smaller breeds need less space than the figures above?: Generally yes, proportionally, but the published standards are written for standard-size hens. If you're keeping a smaller breed, treat these figures as a safe upper bound rather than assuming a precise reduction.
Does more coop space mean I need fewer nest boxes?: No — nest box count is driven by flock size (commonly one box per five hens), not floor area. A bigger coop with too few nest boxes still causes queuing and egg-laying stress.
Can I legally keep chickens in my back garden?: In most UK residential areas, yes — chickens are the most commonly permitted backyard animal precisely because they're quiet, small and low-impact. Roosters are the main exception: a lot of restrictions target roosters specifically, for crowing noise, while happily permitting hens. Check with your local council for any flock-size cap or registration requirement — our guide to backyard chicken-keeping rules has more detail.
Is there a version of this for the US?: Yes — see our US chicken coop size calculator, based on Cooperative Extension System guidance.

You might also need

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