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Gravel Calculator
Calculate gravel volume needed
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Result
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What this calculator does
Estimates the tonnes of gravel for a bed, path or base layer from area and depth, with the matching volume.
How to use it
- Enter width and length.
- Enter depth in centimeters.
- Set waste and read tonnes and cubic meters.
Formula
baseVolume = Width × Length × Depth/100 metric tonnes = baseVolume × 1.6 × (1 + Waste Margin (%) / 100) Material volume m³ = baseVolume × (1 + Waste Margin (%) / 100)
Formulas are shown in metric units, exactly as the calculator computes them. Imperial entries are converted to metric first. Waste is applied as a multiplier (1 + waste/100).
Areas are in m² and volumes in m³. Centimeters are divided by 100 to give meters.
Variables
| Variable | Unit | Default |
|---|---|---|
| Width | m | 5 |
| Length | m | 10 |
| Depth | cm | 5 |
| Waste Margin (%) | % | 10 |
Worked example
Using the default values of this calculator (Width = 5 m, Length = 10 m, Depth = 5 cm, Waste Margin (%) = 10 %), the calculator returns:
baseVolume = 5 × 10 × 5/100 metric tonnes = baseVolume × 1.6 × (1 + 10 / 100) Material volume m³ = baseVolume × (1 + 10 / 100)
- Gravel Needed: 4.4 t
- Material volume: 2.75 m³
Assumptions and limitations
- Uses a fixed bulk density of 1.6 t/m³; real gravel varies with grading and moisture.
- Compaction is not modelled: compacted layers need more material.
Waste, rounding and buying
Suppliers sell by tonne or bulk bag; ask their density and compare. Allow extra for compaction.
Frequently asked questions
- Are the tonnes metric?
- The result is computed in metric tonnes from t/m³. US short tons are about 10% smaller than a metric tonne, so check what your supplier uses.
- Do I need extra for compaction?
- Usually yes. Increase the waste margin; the calculator does not model compaction.