Tonne to m²
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Density by mix type
| Designation | Description | Density (kg/m³) | Typical use | Standard |
|---|---|---|---|---|
| AC 10 surf | Asphalt concrete surface course, 10 mm | 2,340 | Surface course 25–40 mm | BS EN 13108-1 |
| AC 14 surf | Asphalt concrete surface course, 14 mm | 2,350 | Surface course 40–50 mm | BS EN 13108-1 |
| HRA 30/14 | Hot rolled asphalt with pre-coated chippings | 2,290 | Traditional surface course | BS EN 13108-4 |
| SMA 10 surf | Stone mastic asphalt | 2,400 | High-traffic surface course | BS EN 13108-5 |
| Thin surface course system | Proprietary thin surfacing | 2,320 | Surface course 20–40 mm | BS EN 13108-2 |
| AC 20 bin | Asphalt concrete binder course, 20 mm | 2,360 | Binder course 50–80 mm | BS EN 13108-1 |
| AC 32 base | Asphalt concrete base, 32 mm | 2,370 | Base 80–150 mm | BS EN 13108-1 |
| EME2 | High-modulus base | 2,435 | Heavy-duty base | BS EN 13108-1 / CD 226 |
| Porous asphalt | PA 20 | 2,000 | Drainage surface course | BS EN 13108-7 |
| Recycled planings | Reclaimed asphalt planings | 2,000 | Drives, hardstanding, sub-base | BS EN 13108-8 |
| Type 1 sub-base | Granular sub-base | 2,100 | Unbound sub-base 100–300 mm | SHW Clause 803 |
| Bitumen 40/60 | Paving grade binder | 1,030 | Tack coat and binder only | BS EN 12591 |
Coverage per tonne
| Compacted thickness | m² per tonne | tonnes per 100 m² | tonnes per 1,000 m² |
|---|---|---|---|
| 20 mm | 21.3 | 4.70 | 47.0 |
| 25 mm | 17.0 | 5.88 | 58.8 |
| 30 mm | 14.2 | 7.05 | 70.5 |
| 40 mm | 10.6 | 9.40 | 94.0 |
| 50 mm | 8.5 | 11.75 | 117.5 |
| 60 mm | 7.1 | 14.10 | 141.0 |
| 70 mm | 6.1 | 16.45 | 164.5 |
| 80 mm | 5.3 | 18.80 | 188.0 |
| 100 mm | 4.3 | 23.50 | 235.0 |
| 150 mm | 2.8 | 35.25 | 352.5 |
| 200 mm | 2.1 | 47.00 | 470.0 |
Calculator
Waste and compaction allowance
Loose material behind the paver occupies roughly 20% more volume than the finished compacted surface. Add edge trimming, material left in the vehicle body and normal measurement tolerance, and you need an allowance on top of the calculated tonnage.
| Situation | Allowance | Reason |
|---|---|---|
| Simple rectangle, machine-laid, experienced crew | 5% | Minimal trimming and predictable compaction |
| Standard driveway or car park | 10% | Normal edge detail and some hand work at the perimeter |
| Curved edges or several separate zones | 15% | More offcuts and more hand placement |
| Hand-laid work and small patches | 15% | Hand compaction is less consistent |
| Recycled planings | 15–20% | Higher compaction factor and less predictable spread |
| Unbound granular base | 20–25% | Significant consolidation under the roller |
Round the final figure up to the nearest half tonne. Being short means a cold joint in the middle of the surface and a second delivery charge, which costs far more than the extra material would have.
Standards and who administers them
Surfacing work in the United Kingdom is specified under BS EN 13108 and BS 594987, administered by National Highways and the Specification for Highway Works. In practice that governs three things you will see on any quotation or drawing:
- The mix designation. Each layer has a defined material with a stated aggregate size, binder grade and target void content. This is what determines the density used in your tonnage calculation.
- The layer thicknesses. Minimum and maximum lift thicknesses are tied to the nominal aggregate size, because a lift thinner than about twice the largest stone cannot be compacted and one thicker than about three times it cannot be compacted through.
- Compaction acceptance. Density is normally specified as a percentage of the laboratory maximum rather than an absolute figure, because the maximum varies with the mix design.
For private domestic work none of this is legally binding, but the same physics applies. Asking a contractor which specification they are working to, and getting the compacted thickness written into the quotation in millimetres, is the single most useful thing you can do to make competing quotations comparable.