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Farm shed size calculator
Tell us what's going in the shed and get a starting size: span, length in bays and eaves height. The figures come from published UK guidance (Red Tractor, AHDB, FAS and HSE). Every source is listed below.
Suggested building
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A starting point from published guidance, not a design. A contractor will confirm the layout, structure and planning.
How the calculator works
Each mode starts from the space the animals, bales, machines or grain need, using the figures below. It then lays that space out as a typical portal frame building, adds the passages a farm building needs, and rounds the length up to whole bays. Livestock buildings use 4.8 m bays and storage buildings use 6 m bays, both common in UK farm buildings.
Cattle
Floor area per head comes from the Red Tractor space allowances, which AHDB also publishes. For straw-bedded pens it uses the total area including feeding and loafing; for slats it uses the fully slatted figure. Feed face per head comes from FAS guidance, for restricted or ad lib feeding. The building is made long enough for every animal to reach the feed barrier, with a 5 m drive-through feed passage for a tractor and diet feeder. FAS gives 3.5 m as the minimum height to the lowest point of the roof; the calculator suggests more, so a loader tractor can muck out.
Dairy cubicles
Cubicle sizes come from Red Tractor (2.4 × 1.15 m under 600 kg, 2.5 × 1.2 m over), with 5% more cubicles than cows. Feed alley, cubicle passage and cross-over passage widths follow the DairyCo (AHDB) best practice guide.
Sheep
Floor space per ewe comes from the Code of Recommendations for the Welfare of Sheep, as set out by FAS and Farmers Weekly. Trough space follows FAS (450 to 500 mm per ewe on concentrates, more in late pregnancy). Lambing pens follow Lamlac's guide of about one 2 m × 1 m pen per 8 ewes.
Hay and straw
Stack heights follow HSE guidance: big square bales no more than 10 high on hard standing, and round bale stacks about three times the bale diameter. The stack also stays at least 0.5 m below the eaves. An extra 10% of floor is added for gaps and a working lane.
Grain
Volume is worked out from typical bulk densities: wheat about 0.72 to 0.83 t/m³, with lighter crops such as barley and oats needing more space per tonne. An extra 15% of floor is added because a heap slopes away from the walls, plus room to load. Check densities with your merchant or store manager.
Machinery
Machines are parked side by side, facing the open front, with about 0.9 m between them. The span is the longest machine plus a 1.5 m walkway, and the eaves are the tallest machine plus 0.5 m.
Sources
| Source | Used for |
|---|---|
| Red Tractor Beef & Lamb housing space allowances (also in AHDB Better Returns Beef Manual 6) | Cattle floor area per head by liveweight: straw-bedded total area and fully slatted area. |
| AHDB Better Returns: Improve beef housing (Beef Manual 6) | Ventilation outlet area per animal. |
| FAS / SAC Better Cattle Housing Design | Feed space per head (restricted and ad lib), passage widths, minimum roof height and pitch. |
| Red Tractor Dairy housing space allowances | Cubicle sizes and at least 5% more cubicles than cows. |
| DairyCo (AHDB) Dairy housing: a best practice guide | Cubicle passage, feed alley and cross-over passage widths. |
| FAS Slatted sheep housing made simple, and Farmers Weekly expert guide to sheep housing | Floor space per ewe (lowland and hill, with and without lambs) and trough space per ewe. |
| Lamlac: Housing ewes and lambs | About one individual lambing pen per 8 ewes, at least 2 m × 1 m. |
| HSE: Safe working with bales in agriculture (INDG125) | Big square stacks no more than 10 bales high on hard standing; round bale stacks about 3× bale diameter. |
| FAO bulk density tables | Whole wheat bulk density 0.72 to 0.83 t/m³. |
Questions
How big a shed do I need for 100 cattle?
For 100 growing cattle at 500 kg on straw, Red Tractor allows 5.85 m² each including feeding and loafing space, so about 585 m² of pen area. Add a 5 m drive-through feed passage with pens on both sides and you are looking at roughly a 26 m span × 29 m long building (six 4.8 m bays). Use the calculator above for your own numbers.
How much space does a ewe need in a shed?
Lowland ewes need 1.2 to 1.4 m² each, rising to 2.0 to 2.2 m² with lambs at foot. Hill ewes need a little less. Allow about one individual lambing pen per 8 ewes.
How many round bales fit in a shed?
It depends on bale size and how high you can safely stack. A 4 ft × 5 ft round bale stood on end takes about 1.5 m × 1.5 m of floor. HSE guidance keeps round bale stacks to about three times the bale diameter. The calculator works out the floor area and building size for any number of bales.
How much space does a tonne of wheat take up?
Wheat weighs roughly 0.72 to 0.83 tonnes per cubic metre, so a tonne takes about 1.3 m³. Stored 3 m deep on a flat floor, 1,000 tonnes of wheat needs around 450 m² of floor, before allowing for heap slopes and loading space.
What eaves height do I need for a machinery shed?
Measure the tallest machine that will go inside and add clearance. Many machinery stores are built with 5 m to 6 m eaves. If you will tip trailers or lift with a telehandler inside, you need considerably more height.
Is the calculator a replacement for a builder's design?
No. It gives a sensible starting size based on published UK guidance, so you know roughly what to ask for. A farm building contractor will confirm the layout, the structure to BS 5502, and planning.