Why is there a compaction allowance?

Loose material settles when it is laid and rolled, so the delivered volume has to exceed the finished volume. Ten percent is typical and heavily compacted bases need more.

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Topsoil Calculator

Topsoil by volume and weight. A lawn wants 100 to 150mm and a planting bed 300 to 450mm, and topsoil settles noticeably after laying.

Also called: soil calculator, garden soil quantity.

Tonnes of topsoil

10.73

10.73 tonnes, which is 8.25 m³ of topsoil at 150mm deep over 50 m².

Volume (m³)

8.25

Area (m²)

In cubic feet

291.3

In 25 kg bags

429

Loads at 2.8 m³

2.95

How this is calculated

Method and background

How this is calculated

Area times depth, converted at about 1,300 kg per cubic metre for screened topsoil. Settlement is real, so order against the compacted depth you want rather than the loose depth you lay.

volume = area * depth, plus compaction allowance; mass = volume * bulk density

A: Area (m2)
d: Depth (metres)
density: Bulk density (kg/m3)

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a lawn at 150mm

Length (m): 10
Width (m): 8
Or the area directly (m²): 0
Depth (mm): 150
Bulk density (kg/m³): 1,300
Compaction and wastage: 10%

Tonnes of topsoil17.16

80 * 0.15 * 1.1, at 1300 kg/m³

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a planting bed is deeper

Length (m): 10
Width (m): 8
Or the area directly (m²): 0
Depth (mm): 400
Bulk density (kg/m³): 1,300
Compaction and wastage: 10%

Tonnes of topsoil45.76

boundary

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no area needs nothing

Length (m): 0
Width (m): 0
Or the area directly (m²): 0
Depth (mm): 150
Bulk density (kg/m³): 1,300
Compaction and wastage: 10%

Tonnes of topsoil0

degenerate case

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Method and limits

What it assumes

Screened topsoil at 1,300 kg/m³, which varies with moisture.

What it deliberately does not model

Wet soil is substantially heavier. Unscreened soil contains stone and settles differently.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why is there a compaction allowance?: Loose material settles when it is laid and rolled, so the delivered volume has to exceed the finished volume. Ten percent is typical and heavily compacted bases need more.