Asphalt Tonnes Calculator
Work out how many tonnes of asphalt to order to surface a given area at a chosen compacted thickness. Used by civil contractors, road crews and estimators pricing driveways, car parks and pavement layers.
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Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the area to be paved (m²) and the compacted thickness of the layer (mm).
- Set the compacted (laid) density — 2.4 t/m³ is a sensible default for dense-graded asphalt.
- Add an optional waste/allowance percentage, then read the tonnes required and coverage.
How it works
Asphalt is ordered by mass, so the calculator first finds the compacted volume as area × thickness (with thickness converted from mm to m), then multiplies by the laid density to get tonnes.
An optional waste/allowance percentage is applied on top to cover trimming, uneven subgrade and small overruns. The coverage figure (tonnes per square metre) is handy for quickly scaling a quote up or down.
Worked example
100 m² driveway, 50 mm thick. Volume = 100 × (50/1000) = 5.0 m³. At 2.4 t/m³ with a 5% allowance: 5.0 × 2.4 × 1.05 = 12.6 t. Coverage is 12.6 / 100 = 0.126 t/m².
Common mistakes
- Entering thickness in cm or m instead of mm — 50 mm is 0.05 m, not 50.
- Using a loose/rack density (~1.5–1.6 t/m³) instead of the compacted laid density (~2.3–2.5 t/m³).
- Forgetting a waste allowance, so the delivered load runs short on an uneven subgrade.
Frequently asked questions
What density should I use for asphalt?
Dense-graded hot-mix asphalt is typically 2.3–2.5 t/m³ compacted; 2.4 t/m³ is a common default. Confirm the laid density with your supplier.
How many tonnes of asphalt per square metre?
At 2.4 t/m³, roughly 0.024 t per m² per 10 mm of thickness — so a 50 mm layer is about 0.12 t/m². The tool shows the exact coverage for your inputs.
Does this include the waste allowance?
Only if you enter one. The waste/allowance percentage is optional and defaults to 0%; 5–10% is common to cover trimming and subgrade variation.
Is this compacted or loose volume?
It uses the compacted (in-place) thickness and laid density, which is how asphalt is specified and supplied by tonnage. No separate compaction factor is needed.
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Tip: Enter any known values to calculate the remaining results.
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