Formula and example
How it is calculated
Volume = area × thickness/100 × (1 + allowance/100); mass = volume × bulk density, with thickness in centimetres
Worked example
20 m² at a depth of 5 cm equals 1 m³; a 10% allowance gives 1.1 m³.
Things to check
- The default density is an example. Moisture, particle size and compaction change the actual bulk density; use the supplier's figure where possible.
- Use one currency consistently. Examples use euros; the calculation works with any currency.