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Calculating topsoil requirements

To calculate how much topsoil you need, simply measure the dimensions of the area you wish to cover and multiply this by the depth required. Measuring in metres is simplest, as this will give you the volume of topsoil you need in cubic metres.

For example: A site has an area of 10m x 15m and needs a coverage of 150mm.

10 x 15 x 0.15 = 22.5m3

Once you know the volume in cubic metres you can work out how many bulk bags are needed by dividing by the volume in a bag. Bulk bags vary in size, so do check how much is in a bag when comparing different products.

Loam in Hands

Topsoil Calculator

You can also enter your measurements into Rolawn’s handy Topsoil Calculator which will give you an indication of how many bags of the different Rolawn topsoils are needed. The calculator will also convert yards, feet & inches if your measurements aren’t in metres and millimetres. Do make sure you select the correct units in the calculator.

Loose Topsoil

Rolawn topsoil is sold in bulk bags, however if you need to calculate the tonnage required when buying loose topsoil, you’ll need to check the bulk density of the product, as this will vary depending on the type of topsoil and its make up. As a general rule, a tonne of a standard topsoil equals approximately 0.67m3. Divide the cubic metres required by 0.67 to give you the tonnage.

Recommended depths

The depth of imported topsoil required will depend on the site, the existing soil and what you are going to use the area for. In new properties the soil is often shallow and poor quality, therefore importing the full recommended depth of topsoil may be required. If the soil structure is poor, incorporating a soil improver may be the best option. If your existing soil is reasonably good quality, a shallower layer of new topsoil may be all that’s required to bring it up the required depth or assist with providing a level surface and good tilth.

Lawns

The recommended depth of topsoil for creating lawns from turf or seed is 100 to 150mm.

General gardening

150 to 200mm of soil is usually sufficient for most planting.

Vegetable growing

The depth of topsoil required for vegetables will vary depending on what you plan to grow. Root vegetables such as potatoes and carrots will need 300 to 400mm, whereas vegetables such as salads, beans and courgettes will need a depth of 150 to 200mm.

Use our Product Calculator to calculate how much topsoil you need.