Working out how much gravel to order for a garden bed, path or driveway? This free gravel calculator estimates the volume in cubic metres and the weight in tonnes for common Australian aggregates. Enter your length, width and depth, choose your material, and get an instant estimate — with 10% extra for compaction and wastage included.
Gravel Calculator
How to use the calculator
- Measure your area in metres and enter the length, width and depth — use 0.05 m for a 50 mm path top-up or 0.1 m for a new 100 mm layer.
- Choose your gravel type; each material uses its typical bulk density in tonnes per cubic metre.
- Keep the 10% extra box ticked to allow for compaction and spillage, then press Calculate.
Related calculators: Pea Gravel Calculator, Driveway Gravel Calculator, Gravel Tonnage Calculator, Blue Metal Calculator
FAQs
How many tonnes of gravel are in a cubic metre?
It depends on the material. Most crushed aggregates like 20mm blue metal weigh about 1.6 tonnes per cubic metre, while denser crushed rock is around 1.8 t/m³. The calculator applies the density for the material you select.
How deep should gravel be?
For garden paths and decorative areas, 40–50 mm of compacted gravel is usually enough. Driveways need 100 mm or more over a prepared base. Always enter the compacted depth you want, not the loose depth.
Should I order extra gravel?
Yes — allow 10% extra for compaction, uneven ground and spillage during delivery and spreading. The calculator adds this automatically when the box is ticked.