Gravel volume to tonnes: ask for the right bulk density

The geometric volume of a bed comes from its area and depth. Converting that volume to a mass requires bulk density. This is the density of the supplied aggregate including spaces between particles, not the solid-rock density.

A worked example

Item	Example or check
Bed	6 m × 2 m
Depth	0.05 m
Net volume	0.6 m³
With 10% extra	0.66 m³
At illustrative 1,600 kg/m³	1,056 kg = 1.056 tonnes

Check the assumptions

Ask the supplier whether their quoted density describes loose or compacted material and whether moisture changes the delivery estimate. A calculator default cannot identify the exact aggregate in a local yard.

Try the supplier’s low and high density estimates. At 1,400 kg/m³, 0.66 m³ weighs 924 kg. At 1,800 kg/m³, it weighs 1,188 kg. That difference can matter to both price and transport planning, even though the measured bed volume has not changed.

Before using the estimate

The calculator does not specify compaction, load-bearing design or vehicle payload. Delivery and safe handling decisions need separate checks.

Open the Gravel Calculator and compare your measurements with the example.