Why is there a compaction allowance?

Loose material settles when it is laid and rolled, so the delivered volume has to exceed the finished volume. Ten percent is typical and heavily compacted bases need more.

Construction & HomeoutdoorUnited States only

Asphalt and Driveway Calculator

Asphalt tonnage from area and compacted thickness. Asphalt is dense at around 2,400 kg per cubic metre, so a small area is a surprisingly large delivery.

Also called: asphalt tonnage, blacktop calculator.

Tonnes of asphalt

6.6

6.6 tonnes, which is 2.75 m³ of asphalt at 50mm deep over 50 m².

Volume (m³)

2.75

Area (m²)

In cubic feet

97.1

In 25 kg bags

264

Loads at 2.8 m³

0.98

How this is calculated

Method and background

How this is calculated

Area times compacted thickness gives the finished volume, and density converts it to tonnes. Thickness is quoted compacted, so the material laid loose is roughly a quarter thicker before rolling, which the allowance covers. A residential driveway is typically 50mm of surface course over a base; a road is considerably more in several layers.

volume = area * depth, plus compaction allowance; mass = volume * bulk density

A: Area (m2)
d: Depth (metres)
density: Bulk density (kg/m3)

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a driveway at fifty millimetres

Length (m): 20
Width (m): 4
Or the area directly (m²): 0
Compacted thickness (mm): 50
Compacted density (kg/m³): 2,400
Compaction and wastage: 10%

Tonnes of asphalt10.56

80 * 0.05 * 1.1, at 2400 kg/m³

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doubling the thickness doubles the tonnage

Length (m): 20
Width (m): 4
Or the area directly (m²): 0
Compacted thickness (mm): 100
Compacted density (kg/m³): 2,400
Compaction and wastage: 10%

Tonnes of asphalt21.12

boundary

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no area needs nothing

Length (m): 0
Width (m): 0
Or the area directly (m²): 0
Compacted thickness (mm): 50
Compacted density (kg/m³): 2,400
Compaction and wastage: 10%

Tonnes of asphalt0

degenerate case

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Method and limits

What it assumes

The thickness entered is the finished compacted thickness.

What it deliberately does not model

Density varies with the mix, from about 2,300 to 2,500 kg/m³.
The base layer beneath is a separate quantity.

Formula version 1.0.0 · definition 1.0.0 · United States · Report a problem with this calculator

Frequently asked questions

Why is there a compaction allowance?: Loose material settles when it is laid and rolled, so the delivered volume has to exceed the finished volume. Ten percent is typical and heavily compacted bases need more.