How much soil do I need?

Convert a rectangular bed’s dimensions and fill depth into cubic metres, litres, and whole bags.

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ToolSoil Calculator
Input
Output
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How it works

Depth is divided by 100 to convert centimetres to metres before length × width × depth produces cubic metres. Multiplying by 1,000 gives litres, and dividing by the bag’s printed litre volume rounds upward to the number of bags to buy.

Formula
volume m³ = length m × width m × depth cm ÷ 100
  • Every dimension and bag size is required because a 30 cm raised bed and a 5 cm mulch layer are different orders.
  • No weight estimate is shown because wet topsoil, compost, and bark mulch do not share a defensible tonnes-per-cubic-metre constant.

Worked example

A raised bed
2m by 1m, filled to 30cm
Input
											Length m: 2
Width m: 1
Depth cm: 30
Bag size litres: 50
Output
												Cubic metres: 0.6
Litres: 600
Bags needed: 12

When to use this

Raised vegetable beds use deep topsoil mixtures, new lawns use a measured topsoil layer, and borders use shallow bark or compost mulch sold by the litre.

Edge cases

  • A 30 cm fill is treated as 0.30 m; using 30 directly would make the order one hundred times too large.
  • A 601 L requirement in 50 L bags rounds up to 13 because twelve bags provide only 600 L.
  • Fresh fill can settle after installation, but no arbitrary compaction percentage is added; the RHS advises letting a new bed settle and topping it up.

References