Topsoil Calculator

How the topsoil calculation works

Topsoil volume (m³) = length × width × depth in metres. Convert centimetres to metres before calculating the volume.

Worked example: how much topsoil do I need?

For a 5 m × 3 m area at 10 cm depth, the area is 15 m² and the basic topsoil volume is 1.5 m³. With a 5% planning allowance, the order quantity is about 1.575 m³.

Guide: measuring topsoil requirements

For measurement steps, depth examples, conversions, settling and ordering tips, read the Topsoil Calculator Guide →.

Topsoil for garden beds

Measure the actual area that will receive topsoil. If a bed contains other materials or has different depths, calculate each section separately and add the volumes.

Topsoil for lawn areas

For lawn renovation or top-dressing, use the intended average depth rather than the full height of an existing lawn or garden bed. Uneven ground may require separate sections for a better estimate.

Topsoil depth matters

A small change in depth can significantly change the volume. Measure depth in several places where the ground is uneven and use a realistic average.

Bagged versus bulk topsoil

Bulk topsoil is often sold by cubic metre, while bagged products are usually labelled in litres. Multiply cubic metres by 1,000 to convert the result to litres, then compare with the package size.

Allowing for settling and uneven areas

A modest allowance may help with settling, trimming and small measurement differences. Avoid adding a large arbitrary percentage when the supplier already provides a recommended allowance.

Common topsoil calculation mistakes

• Using centimetres as though they were metres.
• Calculating the whole bed volume when part of it will contain drainage or another material.
• Ignoring different depths across an uneven area.
• Ordering by weight without checking the supplier's stated volume or density.

Frequently asked questions

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