How the asphalt calculator works
Asphalt plants weigh every truck on a weighbridge, so your order is placed in tonnes (or US short tons of 2,000 lb) rather than in cubic metres. The calculator works out the compacted volume of the layer, multiplies it by the density of the rolled mix and adds an allowance for feathered edges, low spots and material left in the truck bed.
Tons = length × width × compacted thickness × density × (1 + allowance ÷ 100)Density matters more than people expect. A dense-graded surface mix compacts to roughly 2.3 t/m³, the same as about 145 lb/ft³, but porous mixes can be closer to 2.0 t/m³ and some stone-rich mixes exceed 2.4 t/m³. For US jobs a handy shortcut follows from the same figure: one square yard, one inch thick, weighs about 110 lb.
Worked example
A single-car driveway measures 15 m by 3.5 m, or 52.5 m². At 6 cm compacted it holds 52.5 × 0.06 = 3.15 m³. At 2.3 t/m³ that is 7.25 t, and with a 5% allowance the order is 7.61 t, which works out at 145 kg of mix per square metre. The imperial version, 50 ft by 12 ft at 2.5 in, gives 600 × 2.5 ÷ 12 = 125 ft³, or 18,125 lb at 145 lb/ft³. Divide by 2,000 and add 5%: about 9.5 US tons, one small tandem truckload.
Tonnage by thickness
| Compacted thickness | Per 100 m² (at 2.3 t/m³) | Imperial thickness | Per 1,000 ft² (at 145 lb/ft³) |
|---|---|---|---|
| 4 cm | 9.2 t | 1.5 in | 9.1 US tons |
| 5 cm | 11.5 t | 2 in | 12.1 US tons |
| 6 cm | 13.8 t | 2.5 in | 15.1 US tons |
| 8 cm | 18.4 t | 3 in | 18.1 US tons |
| 10 cm | 23.0 t | 4 in | 24.2 US tons |
Many European driveways are built in two courses: a binder course of about 6 cm and a finer wearing course of 3–4 cm on top. Run the calculator once for each course, because the two mixes are ordered and delivered separately.
What sits under the asphalt
The blacktop is only the skin. A residential drive normally needs 15–20 cm (6–8 in) of compacted crushed stone underneath, more on clay or where trucks will turn. That base is a separate material, sized by volume with the gravel calculator. Skimping on it is the most common reason a new drive cracks and ruts within a few winters.
Tips for ordering hot mix
- Enter the rolled thickness. Loose asphalt behind the paver is about 20–25% thicker than the finished layer; the density figure already refers to the compacted state.
- Check the minimum load. Plants often charge a small-load fee below about 5 to 10 tons.
- Plan for heat and time. Hot mix has to be spread and rolled while still hot, so a long haul or a cold, windy day shortens the working window.
- Build in a fall. A crossfall of around 2% (1/4 in per foot) sheds rainwater away from the house and garage.
- Wait before sealing. Sealcoat is usually applied after the surface has cured for six months or more, not on the day of paving.
Frequently asked questions
How many tons of asphalt do I need for a 20x20 driveway?
400 ft² at 2 in compacted is 66.7 ft³, about 9,700 lb or 4.8 US tons at 145 lb/ft³; with 5% extra order roughly 5.1 tons. At 3 in it is about 7.6 tons.
How much does a ton of asphalt cover?
One US ton covers about 80 ft² at 2 in or 55 ft² at 3 in. One metric tonne covers about 8.7 m² at 5 cm and 7.2 m² at 6 cm.
How thick should an asphalt driveway be?
For cars, 5–7.5 cm (2–3 in) of compacted asphalt over 15–20 cm (6–8 in) of compacted stone base is usual. Drives used by delivery trucks or campers need a thicker, often two-layer, build-up.
What is the density of asphalt?
Compacted dense hot-mix asphalt weighs about 2.3 t/m³, equal to roughly 145 lb/ft³ or about 2 US tons per cubic yard.
How many square metres does a truckload of asphalt cover?
A 20 t load covers about 145 m² at 6 cm compacted, or about 174 m² at 5 cm, at a density of 2.3 t/m³.
Last reviewed: 2026-09-27 · How we calculate