Chicken Coop Size Calculator
Under-sizing a coop or run is one of the most common mistakes new keepers make, and it can lead to stressed, unhappy birds and more frequent pecking or health issues. Enter the number of chickens in your flock below to get recommended coop, run and nest box sizes.
Work out the coop and run size you need
Enter the number of chickens in your flock.
For 6 chickens, you should aim for a coop floor area of:
1.8m²
Plus a run of at least 6.0m² for free movement, and 2 nest boxes shared between the flock.
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- Weatherproof asphalt roof
- Attached run for daytime grazing
- Pull-out tray for easy cleaning
Cons
- Timber needs annual wood treatment
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Pros
- Twin-wall insulated plastic keeps hens warm and cool
- Predator-proof locking system
- Easy-clean, no crevices for red mite
Cons
- High upfront cost versus a wooden coop
£57.99
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- Angled barrier design deters cats from climbing over
- Fits most existing fence tops without major tools
- Keeps cats safely contained in the garden
Cons
- Needs a fence at least 1.5m tall to work well
Frequently asked questions
How much coop space does each chicken actually need?
A minimum of around 0.3 square metres of floor space per bird inside the coop is the standard backyard guidance, giving each hen enough room to move, perch and settle in comfortably overnight without overcrowding.
Do chickens need a separate run as well as a coop?
Yes — the coop is really just for sleeping, sheltering and laying, while a run gives the flock room to forage, dust-bathe and move around during the day, and it needs considerably more space per bird than the coop itself.
How many chickens can share one nest box?
Around three to four hens can comfortably share a single nest box, since they don't all lay at exactly the same time, though it's worth adding an extra box if you notice queuing or hens laying outside the boxes.
What happens if I don't give my chickens enough space?
Overcrowding a coop or run tends to lead to stress, feather-pecking and a higher risk of disease spreading through the flock, so it's worth erring on the generous side, especially if you plan to add more birds later.
How this calculator works
This calculator uses standard UK measurements to estimate the necessary space for your chicken keeping setup. It takes into account the minimum recommended floor area per bird inside the coop, the required square meterage of outdoor run space, and the dimensions needed for a comfortable nest box. The primary assumption is that each adult hen needs approximately 0.37m³ (or 1.34 sq ft) of floor space within the coop to prevent overcrowding and promote healthy behaviour.
The calculator then multiplies these figures based on your chosen flock size, providing you with an estimated volume for the coop and run, and a corresponding nest box dimension. It’s important to note that this is a starting point – factors like breed, age of the hens, and local climate can influence space requirements. Always prioritise quality construction and adequate ventilation.
Chicken Breed Size Guide (UK)
| Breed | Average Weight (kg) |
|---|---|
| Rhode Island Red | 3.6 |
| Plymouth Rock | 4.5 |
| Wyandotte | 4.0 |
| Orpington | 6.8 |
| Sussex | 5.4 |
| Leghorn | 1.8 |
Worked example: 6 Rhode Island Reds
Let’s calculate the space needed for six Rhode Island Red chickens, which typically weigh around 3.6kg each. Using the calculator with this information, we determine a minimum coop floor area of approximately 2.27m³ (based on 0.37m³/hen). This translates to roughly 8.95 square feet (or 0.83 m²). Adding in a run size recommendation of 1.5m²/hen gives us a total run area of 9m².
The calculator then suggests nest box dimensions of approximately 60cm x 45cm x 45cm for each hen – this would accommodate the six birds comfortably with some extra space. This equates to roughly £75 - £120 based on standard wood construction costs in the UK, depending on the quality and size of materials chosen. Remember to factor in additional ventilation and secure locking mechanisms when building your coop.
More questions answered
What does ‘m³’ mean?
M³ stands for cubic meters – a unit of volume measuring three-dimensional space. It's used here to represent the internal space needed within your chicken coop and run.
How many hens can I realistically keep in a small garden?
This depends heavily on your garden size and the type of run you plan to build. A minimum of 30m² of outdoor space is generally recommended for six hens, but larger breeds need more room. Consider using fencing or netting to contain them effectively.
What if I want a mixed flock (e.g., hens and chicks)?
Younger chicks require significantly less space than adult birds, so you'll need to adjust the calculations accordingly. Reduce the recommended floor area per bird to 0.18m³ for chicks until they reach maturity.
How does the breed of chicken affect my calculations?
Larger breeds like Orpingtons require significantly more space than smaller breeds such as Leghorns. Always consult a breed-specific guide to understand their adult size and associated needs.
What are the minimum dimensions for a nest box?
A good rule of thumb is 60cm x 45cm x 45cm – this provides enough space for a hen to comfortably lay an egg without feeling cramped. Smaller boxes can cause stress and potentially lead to broken eggs.
Do I need to include any extra space in my calculations?
Always add a buffer of at least 10% to account for potential growth, accessories (feeders, waterers), and general comfort. This will ensure your chickens have enough room to move around freely.
What about ventilation – does that affect the space calculation?
Adequate ventilation is crucial for healthy chickens. It doesn't directly impact the volume calculations but you must factor in space for vents and airflow, ensuring a well-ventilated coop.
Can I use this calculator to determine the size of my feed storage area?
No, this calculator focuses solely on coop and run dimensions. You’ll need a separate calculation or guide to determine suitable feed storage capacity based on your flock's needs.
My chickens are very active – does that mean I need more space?
Yes, highly active breeds will require a larger run area to allow them sufficient exercise and prevent boredom. Consider incorporating features like dust bathing areas and perches for enrichment.
What if I'm building a mobile chicken coop (a ‘chicken ark’)?
Adjust the calculations based on the available space within your ark. Ensure adequate ventilation, secure locking mechanisms, and consider the weight limitations of your chosen vehicle when transporting your flock.