Gravel and sand calculator

Calculating gravel and sand quantities

Bulk materials are ordered in tonnes but measured in cubic metres — so bulk density matters: ~1.5–1.6 t/m³ for sand, ~1.4–1.5 t/m³ for gravel depending on fraction. Compaction shrinks the layer, so add a compaction factor of ~1.2–1.3 to the ordered volume.

The calculator converts area and layer thickness into cubic metres and tonnes with a reserve — handy when ordering full loads. Pick the fraction by task: 0–32 or 0–45 for load-bearing layers, finer for levelling, washed sand for paving joints.

Converting cubic metres to tonnes

Aggregate or sand volume equals area × layer thickness. To obtain tonnes, multiply volume by the bulk density of the selected material. Density is not universal; it varies with grading, moisture and compaction.

The calculator lets you change density and compaction allowance. Compare the final order with the supplier’s stated weight per m³ and vehicle payload.

• Convert thickness to metres before multiplying.
• Calculate separate gradings separately.
• Check whether the supplier prices per tonne or per m³.