How to Calculate Sand
Learn how to estimate sand volume from area and depth.
Use area × depth
For a rectangular area, multiply length by width. Convert the depth to metres, then multiply area by depth to get cubic metres.
Example
A 6 m × 4 m area is 24 m². At 5 cm depth, the depth is 0.05 m, so the volume is 1.2 m³. A 10% allowance would make the planning quantity about 1.32 m³.
Why actual quantities vary
Sand can settle, compact and contain moisture. Low spots can also increase the quantity required. Ask the supplier how their material is sold and whether the quoted quantity is based on loose or compacted volume.
Related tool
Convert the depth before calculating
The key step is to express depth in metres. For example, 25 mm is 0.025 m, 50 mm is 0.05 m and 100 mm is 0.10 m. Multiply the area in square metres by the depth in metres to get cubic metres. To convert cubic metres to litres, multiply by 1,000.
Worked example: a garden bed
A bed measuring 6 m by 4 m has an area of 24 m². If the specified sand layer is 50 mm deep, the volume is 24 × 0.05 = 1.2 m³, or about 1,200 litres. A 10% planning allowance gives 1.32 m³, or 1,320 litres. This is a geometric estimate; it does not predict compaction or account for uneven ground.
When the shape is not rectangular
For an L-shaped area, divide it into two non-overlapping rectangles, calculate each area, then add the results. For a circular area, use the appropriate circle-area formula before multiplying by depth. Avoid counting the same section twice when splitting a shape into smaller pieces.
Ordering and site checks
- Ask the supplier whether the quoted quantity is in cubic metres, tonnes or bags.
- Bulk density varies with grain size, moisture and product type, so do not convert volume to tonnes using an assumed density unless the supplier provides it.
- Keep drainage and the intended use in mind; sand is not a substitute for a specified structural base.
- Measure depth at several points if the ground is uneven.
For related estimates, see the Sand Calculator, Soil Calculator and Paver Base Calculator.