How thick should tarmac be for a driveway?

A domestic driveway typically needs 50mm of base course (20mm dense bitumen macadam) plus 25mm of wearing course (6mm close-graded macadam), totalling 75mm of tarmac. For commercial or heavy vehicle use, increase the base course to 60-80mm. Both layers are laid separately and compacted with a roller.

How many tonnes of tarmac per square metre?

Tarmac (asphalt) has a compacted density of approximately 2.3 tonnes per cubic metre. At standard driveway thickness (50mm base + 25mm wearing = 75mm total), you need about 0.17 tonnes (170 kg) per square metre. A typical 50 m² driveway requires around 8.6 tonnes of tarmac.

What sub-base do I need under tarmac?

Tarmac driveways need a compacted Type 1 sub-base (crushed limestone or granite) at least 150mm deep for domestic use, or 200mm+ for heavy vehicles. The sub-base must be compacted in layers (maximum 150mm lifts) using a vibrating plate or roller. Type 1 aggregate weighs approximately 1.8 tonnes per m³.

Does a tarmac driveway need planning permission?

If your front garden tarmac driveway drains to a permeable area (lawn, border or soakaway), no planning permission is needed under permitted development rules. If the entire surface is impermeable and drains to the road, you'll need planning permission. This applies to areas over 5 m² in England.

How much does tarmac cost per tonne?

Tarmac typically costs £75-110 per tonne for materials, depending on the grade and your location. A typical 50 m² driveway needs approximately 8-9 tonnes, so material cost is around £600-1,000. Installation labour, plant hire (roller) and skip for excavated soil are additional costs.

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Tarmac Driveway Calculator — Tonnage & Sub-base

Calculate tarmac tonnage for base course and wearing course, sub-base aggregate and edge restraint.

Driveway Area

Total area to be surfaced

Usage Type

Affects sub-base depth

Tarmac Price

Sub-base Price

Edge Restraint Length

Perimeter needing kerbs/edging

Edge Restraint Price

How We Calculate This

This calculator determines tarmac tonnage and sub-base aggregate needed for a tarmac (asphalt) driveway or hardstanding.

Tonnage formula

Tonnes = Area x Depth(m) x Density(2.3 t/m³) x (1 + Wastage%)
Base course (20mm DBM) at 50mm + Wearing course (6mm close-graded) at 25mm.

Sub-base

Type 1 sub-base at 150mm (domestic) or 200mm (commercial), density 1.8 t/m³. Edge restraint kerbs or edging prevent the tarmac spreading.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.