Gravel starts as an area but is purchased by volume or weight. The Gravel calculator connects area, depth, density and packaging.
A 30 m² area at 6 cm depth needs 30 × 0.06 = 1.8 m³. With 5% allowance this becomes 1.89 m³. At 1.6 t/m³, the weight is about 3.02 tonnes.
Density matters
The m³-to-tonne conversion is only as good as the density value. Different aggregates, grading and moisture can change it. Use the supplier’s figure whenever possible.
Also distinguish the required finished depth from loose material before compaction. A technical sub-base may need a project-specific compaction allowance.
Bulk, big bags or small bags
Packaging introduces another rounding step. At 800 kg per big bag, 3.02 t requires four bags, or 3.2 t purchased. Small bags can be convenient for tiny jobs but quickly become impractical for several tonnes.
Compare not only unit price but also delivery, handling, access and packaging surplus.
For drainage or an access path, levels may be as important as quantity: use the Slope calculator. For adjacent concrete work use the Concrete calculator.
The reliable workflow is area → depth → volume → allowance → density → weight → packaging. Keeping every step visible prevents the common confusion between m², m³ and tonnes.
