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Topsoil Calculator
Topsoil for beds and lawns — area and depth in, volume and bags out.
Topsoil volume
How it works
Volume (m³) = area (m²) × depth (cm) ÷ 100 Bags = ceil(volume in litres ÷ 25) Example: 10 × 15 ÷ 100 = 1.5 m³
Worked example: a 10 m² bed at 15 cm deep needs 10 × 15 ÷ 100 = 1.5 m³ of topsoil, which is 1,500 litres, or ceil(1,500 ÷ 25) = 60 bags of 25 litres.
Frequently asked questions
How deep should topsoil be?
For a new lawn, 10–15 cm is typical. For raised beds, 20–30 cm gives roots more room.
Is topsoil the same as compost?
No. Topsoil is the growing medium itself; compost is added to it to improve structure and fertility, not used in place of it.
How heavy is a cubic metre?
It varies a lot with moisture, but roughly 1.6 tonnes per cubic metre when damp. Order by volume, not weight, unless your supplier sells by the tonne.
Should I level it before planting?
Yes. Spread it, rake it level, water it once so it settles, then top up any low spots before planting.
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