How to Calculate Tarpaulin Size for Farm, Vehicle and Storage Cover

Choosing the correct tarpaulin size is important because a sheet that is too small will not cover the item properly, while a sheet that is too large can be difficult to secure in wind and rain. The right size depends on the object dimensions, how much side coverage you need and how the tarpaulin will be tied.

Basic Tarpaulin Size Formula

Measure the length, width and height of the item or area you want to cover.

Required tarp length = object length + front drop + rear drop

Required tarp width = object width + left drop + right drop

Example 1: Farm Material Stack

If a stack is 12 ft long and 8 ft wide, and you want about 2 ft of coverage on each side:

• Length required: 12 + 2 + 2 = 16 ft
• Width required: 8 + 2 + 2 = 12 ft

Choose the nearest available tarpaulin size that is equal to or slightly larger than 16 × 12 ft.

Example 2: Vehicle Cover

For a vehicle or trailer, measure the total length and width across the widest points. Add enough material to cover the sides and allow room for tying. If the vehicle has a high cabin or load, include the extra height in your calculation.

Example 3: Storage and Construction Cover

For stored equipment, building materials or temporary construction protection, measure the complete footprint and decide whether the tarpaulin only needs to protect the top or also the sides. A larger overlap is useful where rain can enter from the edges.

How Much Extra Tarpaulin Should You Allow?

In many applications, allowing approximately 1–2 ft extra on each side makes tying easier. Larger objects or exposed outdoor locations may need more overlap. Avoid choosing an excessively oversized sheet because loose material can flap in the wind and place more stress on eyelets and tie points.

Choosing GSM After Choosing the Size

Size tells you how much area the tarpaulin can cover, while GSM indicates the material weight and generally relates to the grade of the sheet. Light-duty temporary covers can use lower GSM options, while repeated outdoor, transport and demanding applications usually benefit from heavier grades.

Read our 90 GSM vs 120 GSM vs 200 GSM tarpaulin guide for help choosing a suitable grade.

Measure Before You Order

Measure the actual object rather than estimating. Consider protruding parts, height, overlap and where ropes or other fasteners will be attached. If your calculated size falls between two available sheet sizes, the next larger suitable size is usually the safer choice.

Browse our Tarpaulin collection to compare available brands, GSM grades and sizes.

Frequently Asked Questions

Should a tarpaulin be exactly the same size as the object?

Usually no. Extra material is useful for overlap, tying and side protection.

How do I calculate a tarp for full side coverage?

Add the required drop on both sides to the width and add the front and rear drop to the length.

Should I buy the next larger size if my calculation falls between two options?

In most cases, yes. A slightly larger sheet is easier to secure than one that is too small, provided the excess material can be tied properly.