Sand Calculator
Calculate how much sand a job needs by volume and weight, for bedding, backfill or a sandpit.
How to use this calculator
- 1Measure the area. For an irregular space, split it into rectangles, work each out, and add them.
- 2Set the unit you measured in — the calculator converts everything for you.
- 3Check the coverage figure against the bag or tin you are actually buying; it varies between brands.
- 4Leave the waste allowance on. Running short mid-job costs far more than one spare unit.
How the calculation works
Units = ⌈ (Area × Depth × (1 + waste)) / Volume per unit ⌉- Area
- Surface area of the job
- Depth
- How thick the material is laid
- waste
- Allowance for cuts, breakage and spillage
- ⌈ ⌉
- Round up — you cannot buy a fraction of a unit
Every dimension is converted to metres internally, so feet, yards and metres can be mixed with inches or centimetres without error.
Sand is sold by weight but used by volume, so the density figure is what links them. Dry sand runs about 1.6 t/m³; damp sand is heavier, and compacted or wet sand heavier still.
A typical paving bedding layer is 25–50 mm deep. Deeper is not better — an over-thick bedding layer compresses unevenly and lets pavers settle.
Worked example
A 20 × 12 ft area
- 1.20 ft × 12 ft = 240 sq ft, which is 22.30 m².
- 2.At the depth set above, that gives the volume shown in the result.
- 3.A 5% waste allowance is added, then the figure is rounded up to whole tonnes.
Result: See the result panel — it updates live as you change the numbers.
What this assumes, and where it stops
Assumptions
- The area is flat and regular as described. Slopes, steps and obstructions change the quantity.
- Coverage figures are the manufacturer’s stated values, which assume good conditions and an even surface.
- Sand is dry and loose at roughly 1.6 tonnes per cubic metre. Adjust the volume-per-tonne figure for damp or compacted material.
Limitations
- This estimates material only — not labour, tools, delivery, hire or disposal.
- Manufacturer coverage varies between brands and batches. Always check the packaging.
- Density varies with moisture and grade. Wet sand can be 20% heavier per cubic metre than the dry figure used here.
- Does not account for sand lost into an uneven or permeable sub-base, which on rough ground can be significant.
Common questions
How many cubic metres is a tonne of sand?
About 0.625 m³ for dry sand, since dry sand weighs roughly 1.6 tonnes per cubic metre. Damp sand is denser — closer to 1.8–2.0 t/m³ — so a tonne of it occupies less volume. Suppliers quote by weight, so the density assumption matters when ordering.
How deep should bedding sand be for paving?
Typically 25–50 mm of sharp sand over a compacted sub-base. Going deeper is counterproductive: a thick bedding layer compresses unevenly under load and lets pavers sink or rock. Structural support should come from the sub-base, not the sand.
Formula and content last reviewed on .
Results are estimates for information only, not professional advice.
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