Chicken care

Chicken Coop & Run Size Calculator (UK) — The Evidence-Based Guide

Posted by mallr on

For typical backyard hens, aim for 2.00 m² daytime run per hen (or 1.00 m² for rescued ex-caged hens) and 0.19 m² indoor floor per standard hen at night. Provide ≥ 15 cm perch length per hen and 1 nest box per ≤ 5 hens. More space is always better.

Quick answer: How to size your chicken coop & run:
  • Run area: ~2.00 m² per hen (or 1.00 m² for rescued ex-caged birds).
  • Indoor floor space: ~0.19 m² per standard hen for roosting.
  • Perch length: ≥ 15 cm per hen.
  • Nest boxes: 1 box per ≤ 5 hens.

More space is always better; size up for larger breeds or limited free-range time. A well-sized coop is crucial for preventing health issues. For tips on managing your coop in winter, check out our guide on Chicken Coop Ventilation.

Chicken Coop & Run Size Calculator (UK)

Based on UK welfare guidance (RSPCA/DEFRA/BHWT) interpreted for small flocks.

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Why this calculator

  • Evidence-based: built from BHWT, DEFRA & RSPCA guidance for small UK flocks.
  • Transparent maths: shows run area, coop floor, roost length & nest count.
  • Real-world picks: suggests Nestera sizes (non-affiliate; we use their coops, we use the Penthouse).

How to use it

  1. Enter your flock size and bird type (bantam / standard / large fowl).
  2. Choose your run baseline (BHWT 1–2 m²/hen, or set a custom).
  3. Set free-range time; results update and you can copy a shareable link.

The rules we apply

  • Run area: BHWT minimums — 1.00 m²/hen (ex-caged), 2.00 m²/hen (others). If birds are penned most of the time, aim higher (e.g., ≥ 4.00 m²/hen).
  • Coop floor (night use): conservative backyard rule-of-thumb ≈ 0.19 m²/hen (2 ft²) for standard hens; more for large fowl.
  • Perches (roosts): ≥ 15 cm per hen; space perches sensibly (≈ 30 cm apart).
  • Nest boxes: 1 box per ≤ 5 hens (individual) or 1 m² group nest per 120 hens.

Wondering what chickens to get – try out Chicken Breed Selection tool and read our guide on the Best egg laying chickens for beginners in the UK.

We also have a review of the Nestera Aspen Coop.

FAQ

How big should a chicken run be per hen (UK)?
As a practical minimum, plan 2.00 m² per hen (or 1.00 m² for ex-caged rescues). If hens are penned most of the time, go larger (≥ 4.00 m² per hen). The calculator applies these baselines and adjusts for bantam/large breeds and free-range time.

How much indoor floor space do hens need at night?
A conservative backyard rule is ≈ 0.19 m² per standard hen (2 ft²). Increase for large fowl and poor weather. More space is always better for welfare and ventilation.

How much perch length do I need?
At least 15 cm per hen. Keep perches level and spaced roughly 30 cm apart to reduce pecking and crowding.

How many nest boxes?
1 individual box per ≤ 5 hens, or a group nest at 1 m² per 120 hens. Hens share, so you don’t need one per hen.

Do bantams need less space?
Slightly less than standard hybrids, but still generous. The calculator applies a bantam adjustment — you can always size up.

Can I use this for winter or wet months?
Yes — if your birds spend more time confined, pick a higher run baseline or add extensions. Dry, well-drained flooring (woodchip or sand) helps.

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