Case 1
- Area to pave
- 100m²
- Compacted thickness
- 4cm
- Density of the mix
- 2.5t/m³
10.00t
Open with these valuesAsphalt Calculator
Change any value to update the result.
10.00t
Asphalt needed: 10.00 tExamples
Area × thickness gives the volume, volume × density gives the weight. 100 m² at 4 cm is 4 m³, and at 2.5 t/m³ that is 10 tonnes — the 100 kg/m² a road specification books for a 4 cm wearing course. Asphalt is delivered by the tonne, so the density carries the whole conversion.
The numbers at a glance
Held fixed: Area to pave 100.00 m², Compacted thickness 4.0 cm.
| Density of the mix (t/m³) | Asphalt needed (t) |
|---|---|
| 2.30 | 9.20 |
| 2.40 | 9.60 |
| 2.50Your value | 10.00 |
| 2.60 | 10.40 |
| 2.70 | 10.80 |
Worked examples
Case 2
- Area to pave
- 250m²
- Compacted thickness
- 5cm
- Density of the mix
- 2.5t/m³
31.25t
Open with these valuesCase 3
- Area to pave
- 40m²
- Compacted thickness
- 3cm
- Density of the mix
- 2.5t/m³
3.00t
Open with these valuesHow it's calculated
tonnes = area × thickness × density
- StepEnter the area in square metres — length × width for a rectangle.Area to pave=100m²
- StepSet the compacted thickness in centimetres, not the loose depth.Compacted thickness=4cm
- StepEnter the density; dense-graded hot mix sits near 2.5 t/m³.Density of the mix=2.5t/m³
- ResultRead the tonnage, and add 5–10 % for joints, edges and waste.10.00t
What this number means
Enter the compacted thickness
Hot mix is laid loose and then rolled, and it loses roughly a fifth of its depth doing so. The thickness this calculator wants is the finished one the specification asks for, not the depth behind the paver.
You order tonnes, the area wants a volume
Plants sell hot mix by the tonne, but what fills the area is a volume. Area × thickness gives that volume, and the density is the only bridge between the two.
Where the 2.5 t/m³ default comes from
The road specification behind this calculator books 100 kg/m² for a 4 cm wearing course and 125 kg/m² for a 5 cm binder course. Both are 25 kg per square metre per centimetre, which is 2.5 t/m³.
US figures run lower
The Asphalt Institute quotes 145 lb/ft³ for compacted dense-graded mix, about 2.32 t/m³, while EN 1991-1-1 Table A.6 gives 24 to 25 kN/m³, about 2.45 to 2.55. Across a 100 tonne order that spread is some eight tonnes, so use your supplier's figure.
Commonly misread
MisconceptionThe area needs 4 m³, so I ordered 4 tonnes.
CorrectionThose are different units, and only the density connects them. At 2.5 t/m³ that 4 m³ is 10 tonnes, two and a half times what you ordered.
MisconceptionI entered the layer thickness in metres.
CorrectionThickness is in centimetres here while the area is in square metres. Enter 4 for a 4 cm course, not 0.04.
MisconceptionI used the loose depth I measured behind the paver.
CorrectionRolling takes roughly 20 % of that depth out again. Enter the finished compacted thickness, which is what both the specification and the tonnage are based on.
Reference table
| Area, thickness, density | Volume | Tonnes |
|---|---|---|
| 100, 2.5, 2.4 | 2.5 m³ | 6 |
| 100, 3, 2.5 | 3 m³ | 7.5 |
| 100, 4, 2.5 | 4 m³ | 10 |
| 100, 5, 2.5 | 5 m³ | 12.5 |
| 250, 4, 2.5 | 10 m³ | 25 |
Questions
How much asphalt do I need?
Multiply the area by the compacted thickness, then by the density. For 100 m² at 4 cm the volume is 4 m³, and at 2.5 t/m³ that is 10 tonnes.
How thick should an asphalt layer be?
It depends on the traffic. A wearing course is commonly 3 to 4 cm, a binder course around 5 cm, and a base course 8 cm or more. A private drive is usually built as a 4 cm wearing course over a 5 to 8 cm base.
What density should I enter?
Dense-graded hot mix sits near 2.5 t/m³, which is the default here. The figure moves with the mix — porous asphalt is far lighter, and US practice quotes 145 lb/ft³, about 2.32 t/m³. Use the density on your delivery note when you have one.
How many square metres does a tonne of asphalt cover?
At 2.5 t/m³ one tonne is 0.4 m³, which covers 10 m² at 4 cm or 8 m² at 5 cm. Divide 1 by the density and by the thickness in metres to get the coverage for any other combination.
Should I order a little extra?
Yes. The result is the exact amount for a perfect rectangle at a constant thickness, and real jobs have joints, thickened edges and material left in the truck. Around 5–10 % more is sensible.