Topsoil Volumes: Area Times Depth, in Bags and Cubic Metres
Topsoil maths is just area times depth, but the unit conversions trip people up. This post walks through centimetres, cubic metres, and bag counts.
What is the Topsoil Calculator?
Enter length, width, and depth, and the tool gives the volume in cubic metres and the number of 25-litre bags that volume needs, with a 10 percent allowance shown separately. Bulk topsoil is usually ordered by the cubic metre, so both figures are useful.
How to use it
- Measure the length and width in metres.
- Enter the depth in centimetres.
- Click Calculate Topsoil.
Worked example
5 m by 2 m at 10 cm deep needs 1 cubic metre, or 1.1 with waste, which is 44 bags of 25 litres.
Why do I need a waste allowance for soil?
Ground is rarely level, and soil settles after watering, so the neat volume often falls a little short.
Frequently asked questions
Is bagged or bulk cheaper?
For more than a cubic metre or so, bulk delivery is usually far cheaper per litre.
How deep should new topsoil be?
For lawns, around 10 to 15 cm of good topsoil over the subsoil is a common target.