What size polytunnel: plan beds and paths (UK)

The size calculator performs the same rectangular arithmetic. It does not model a frame, headroom, installation clearances or a particular maker's standard sizes.

Draw the layout you mean to use

Give each bed, path, pot, staging area or work space a place on the sketch. Measure the beds you have in mind and decide where people will walk. Treat the path as part of the plan instead of whatever width happens to be left over.

The calculator is deliberately simple: it assumes identical rectangular beds arranged side by side. It includes one path alongside a single bed, or a path between each neighbouring pair of beds. For a side door, it adds another path-width strip across the end of the layout; for an end door, it adds none. This is the tool's layout convention, not a rule for every tunnel.

Worked example

Suppose the drawing has two beds, each 4 m long and 1 m wide, with a 0.6 m path between them. These are chosen example inputs, not recommended dimensions.

The calculated width is 1 + 0.6 + 1 = 2.6 m. With an end door, the length stays 4 m, so the footprint is 2.6 × 4 = 10.4 m². With a side door, the calculator adds the same 0.6 m path width to the length: 2.6 × 4.6 = 11.96 m².

The total bed area is 2 × 4 × 1 = 8 m². The difference between 8 m² and the footprint is the space assigned to paths in this particular drawing.

Test the drawing on the plot

Mark the proposed outline with string or another temporary marker. Walk the route to the door and place the equipment you expect to move inside. Try the awkward movement too: turning a trolley, carrying a tray or reaching the bed edge. If the space feels wrong, change the drawing and calculate it again.

Look at what the footprint would displace and where tools or empty pots would go. A floor-area number cannot show whether the door is reachable or whether the route works for your routine. If you use particular equipment or need a wider route, measure it and include it in your own sketch; the calculator does not set an access standard.

Check a particular model

Send the drawing to the supplier and request a dimensioned plan for the exact model and size. Ask what its dimensions mean and what clearances the maker specifies. Useful questions include:

• What is the usable width where the beds or staging would sit?
• What height is available where you need to stand or reach?
• What are the clear door dimensions, and which way does it open?
• What installation or maintenance clearances does the maker specify?
• Are the dimensions external, internal or nominal?

Compare the answer with your drawing. Do not assume that a quoted overall width is the same as the usable width for beds. Where two models are being compared, ask the same questions about each.

If the plan does not fit

Try a smaller drawing: remove a bed, shorten one or leave some space for later. Keep the path visible while you revise the plan. Then mark out and check the new version too.

See How we compare for the way we record specifications before making product comparisons. This page does not provide maker dimensions, standard-size matches, crop-spacing advice or installation instructions. It is a way to turn a chosen layout into a footprint to discuss with a supplier.