How this calculation works
Use the bulk density supplied for the actual material and condition, including voids between particles. The example density is an editable assumption, not a specification for all gravel.
Volume = length × width × depth; tonnes = volume × density ÷ 1,000A worked example
A 5 × 4 m area filled 0.1 m deep has volume 2 m³; at 1,600 kg/m³ the mass is 3.2 tonnes.
Good to know
No automatic compaction or waste factor. Moisture and compaction alter bulk density; confirm ordering quantities with the supplier.
Bulk density includes the spaces between particles
A pile’s bulk density is not the same as the density of an individual solid stone. The spaces between particles affect how much mass fits into a given volume, and moisture or compaction can change the result.
The default 1,600 kg/m³ is only an editable example. Using the supplier’s value for the actual material and condition is more defensible than assuming all gravel has one universal density.
Depth needs the same length system as the footprint
A 100 mm layer is 0.1 m deep. Across 20 m², that gives 2 m³, and at the example density the mass is 3.2 metric tonnes. Entering 100 as metres would make the estimate a thousand times too large.
The tool has no automatic waste or compaction correction. If ordered loose material must achieve a compacted thickness, establish the appropriate conversion with the supplier and project specification.
A few questions, answered
Are these metric tonnes?
Yes. One tonne is 1,000 kg.
Does it include compaction?
No. The result follows the volume and bulk density you enter, without an additional compaction factor.