The calculation
| Dimension | Formula |
|---|---|
| Required width | Object width + (2 × required drop) + anchoring margin |
| Required length | Object length + (2 × required drop) + anchoring margin |
| Required drop | How far down the sides the cover must reach, usually the object height |
| Anchoring margin | 0.5 m minimum all round; more in open, windy locations |
The reason people undersize is that the object height is counted once in their head but consumed twice by the sheet — once going down each side. A one-metre-high stack adds two metres to both the width and the length requirement, not one.
Three worked examples
A grain stack
Base 3 m × 3 m, height 1 m, cover must reach the ground. Width = 3 + (2 × 1) + 1 = 6 m. Length = the same, 6 m. A 6 m × 6 m sheet, not the 3 m × 3 m one that matches the footprint.
A truck body
Body 2.2 m wide, load standing 0.6 m above the rail, drop to the tie-down point 0.8 m each side. Width = 2.2 + (2 × 0.8) + 0.6 = 4.4 m. Apply the same logic to length and round up.
A balcony opening
Opening 3 m × 2 m, no drop required but material needed for wrapping and tying. Add 0.4 m on every side: a 3.8 m × 2.8 m requirement, so buy the next size up from 3 m × 2 m rather than the exact match.
Where extra size is not free
Oversizing has real costs — more weight, more folded bulk, more material to control in wind, more cost. The point is not to buy the largest sheet available; it is to buy the size the calculation gives you rather than the size that matches the footprint. Surplus beyond that is waste.
Common sizing mistakes
Matching the sheet to the footprint
The most frequent error. A footprint-sized sheet covers the top and nothing else.
Counting the height once
Height is consumed on both sides. Double it in each dimension.
Forgetting the anchoring margin
A cover that just reaches has nothing left to secure with, so it gets tied at the corners and tears there.
Sizing to the load instead of the vehicle
On any vehicle, size to the body — the load changes trip to trip.
Trading size for GSM
An undersized heavy sheet fails at the shortfall. A correctly sized lighter sheet does not have one.
Custom sizes
Where the calculation lands between standard sizes and the requirement is repeating — a fleet, a yard, a site — custom dimensions manufactured to order usually cost less over time than repeatedly buying the nearest larger standard size. Maximum producible dimensions are set by our loom and lamination equipment and are confirmed at enquiry.
Written by the Double Kissan team at Ashoka Poly Laminators Pvt. Ltd., Bareilly. Last reviewed November 2026.