How much asphalt do I need for a driveway?

Multiply the area (length x width) by your target compacted thickness to get the finished volume, then divide by the compaction factor for your mix type to find the loose volume you need to order, and add a waste allowance on top. For example, a 10 m x 4 m driveway at 5 cm compacted thickness needs 2 m³ of finished asphalt, which works out to roughly 2.54 m³ of loose mix to order once an 8% waste allowance is included, and about 5.18 tonnes to actually purchase.

Why is the tonnage I order more than the finished weight shown?

Asphalt is delivered loose and then rolled into a denser, thinner finished lift, so the loose mix you buy always occupies more volume — and once waste and overage are added, more purchased tonnage — than the compacted, in-place result. This calculator shows the finished in-place weight separately from the purchased tonnage used for the cost estimate precisely to avoid that confusion.

How thick should an asphalt driveway be?

A typical residential driveway surface course is 5-6 cm (2-2.5 in) of compacted dense-graded hot-mix, laid over a properly compacted aggregate base course. Heavier-use driveways, or those needing to carry regular vehicle or delivery-truck weight, are sometimes specified thicker or with an additional binder course beneath the surface course — check local practice or a paving contractor for anything beyond a standard car driveway.

How much does it cost to tarmac a driveway in the UK?

Material cost alone typically runs £85-£110 per tonne, but a fully laid driveway also includes excavation, sub-base, labour and edging, which usually multiplies the raw material cost several times over. This calculator gives you the material tonnage and cost only, as a starting point for pricing or checking a contractor quote.

Asphalt Calculator | Tarmac Driveway Tonnage & Cost

Asphalt Calculator: How Much Asphalt Do You Need?

Asphalt behaves differently from gravel or concrete: it is delivered as loose hot-mix, then rolled and compacted into a denser finished lift. That means the tonnage you order is not simply your driveway's area times its finished thickness times a density figure — it has to account for how much the loose mix shrinks once it is compacted. This asphalt calculator takes your area and your target compacted (finished) thickness, applies a compaction factor for your chosen mix type, and returns the loose mix volume you need to order, the finished in-place tonnage, and an estimated material cost.

It is built for driveway and path paving jobs: homeowners repaving or resurfacing a driveway, and small contractors pricing a quick job. Pick a mix type — standard dense-graded hot-mix, open-graded/porous asphalt, stone-mastic asphalt (SMA), or cold-mix patch material — and the calculator applies that mix's typical compacted density and compaction factor automatically, rather than making you guess a single flat density the way most simple asphalt calculators do. A waste/overage allowance is also built in, since spillage and edge losses are as real on an asphalt job as on any other paving project.

How to Use the Asphalt Calculator

Enter the length and width of the area to be paved, in your chosen unit (m, cm, ft or in).
Enter the compacted (finished) thickness — the depth of the rolled, finished asphalt surface, not the loose mix as it comes off the truck. A typical driveway surface course is 5-6 cm (2-2.5 in).
Choose a mix type: dense-graded hot-mix (the standard choice), open-graded/porous asphalt, stone-mastic asphalt (SMA), or cold-mix patch. Each carries its own typical compacted density and compaction factor.
Optionally override the density or compaction factor with your own figures if your supplier or mix design specifies something different.
Adjust the waste/overage allowance if needed — the default 8% covers typical spillage and edge losses, adjustable up to 15%.
Read off the compacted volume, the loose mix volume you need to order, the finished in-place tonnage, and the estimated material cost.

The Math Behind the Calculation

The finished, compacted volume is the simple part: area x compacted thickness. But asphalt is bought and delivered as loose hot-mix, and loose mix occupies more volume than the same mass does once a roller compacts it. That relationship is the compaction factor: a factor of 0.85 means one cubic metre of finished, compacted asphalt requires 1 / 0.85 = 1.176 m³ of loose mix delivered to the site. So loose volume = compacted volume / compaction factor.

A waste/overage allowance (5-15%, 8% by default) is then applied on top of the loose volume to get the quantity you should actually order, covering spillage, edge losses on an irregular area, and a small ordering safety margin.

The tonnage shown as the finished result is the in-place, compacted weight: compacted volume x compacted density. This figure is deliberately unaffected by the waste allowance, since waste is ordering overage, not extra finished pavement — it describes what actually ends up on the ground once it is rolled. The cost estimate, however, is priced on the tonnage you would actually need to purchase to cover that overage, which is higher than the displayed finished-weight figure, since a supplier invoices what is delivered, not what is left on the road after compaction.

Worked example: a 10 m x 4 m driveway area at a 5 cm (0.05 m) compacted thickness, using dense-graded hot-mix (2,400 kg/m³ compacted density, 0.85 compaction factor) with an 8% waste allowance. Area = 10 x 4 = 40 m². Compacted volume = 40 x 0.05 = 2 m³. Loose volume needed = 2 / 0.85 = 2.353 m³ before waste, or 2.353 x 1.08 = 2.541 m³ to actually order. Finished in-place weight = 2 x 2,400 = 4,800 kg, or 4.8 tonnes. The tonnage you need to purchase to cover the ordering overage works out to 5.184 tonnes, which at a material cost of $140/tonne gives an estimated cost of about $726.

UK Asphalt Standards and Terminology

UK bituminous mixtures are specified under BS EN 13108, and asphalt is almost universally called "tarmac" or "tarmacadam" in everyday domestic use, even though true tarmacadam (tar-bound) has long been replaced by bitumen-bound hot-mix asphalt.
A domestic driveway surface course is typically laid at 40-50 mm compacted thickness over a compacted sub-base, whereas adopted highway work follows the Specification for Highway Works (SHW) — source: BS EN 13108; SHW (Manual of Contract Documents for Highway Works, Volume 1).

Pro Tips and Common Mistakes

At a typical UK material cost of around £95 per tonne, the worked example above (a 10 m x 4 m driveway at 5 cm compacted thickness, dense-graded mix, 8% waste allowance) needs roughly 5.18 tonnes to purchase, costing approximately £492 in material — laying, base preparation and edging kerbs are additional.

Always enter the compacted (finished) thickness, not the loose depth of mix as it is tipped from the truck — the calculator applies the compaction shrinkage for you from that finished figure.
A typical residential driveway surface course is 5-6 cm (2-2.5 in) thick over a compacted aggregate base course; heavier-use areas and any base/binder layers underneath the surface course add to that figure and should be calculated separately.
Dense-graded hot-mix is the standard choice for most driveways. Open-graded/porous asphalt drains better but is less common on private driveways; stone-mastic asphalt is a heavier-duty option; cold-mix is for patching small areas, not for laying a full new driveway.
The tonnage figure this calculator displays is the finished, in-place weight — it is not the same as the tonnage your supplier will actually invoice, since you also need to buy enough loose mix to cover compaction shrinkage and the waste allowance. Use the cost estimate, not the displayed weight, when comparing supplier quotes.
A common mistake is skipping proper base preparation: asphalt laid over a soft, poorly compacted, or poorly drained sub-base will crack and rut regardless of how accurately the surface-course tonnage was calculated.
Freshly laid asphalt typically needs a few days to harden enough for vehicle traffic and longer still (often several weeks) to reach full cure — check with your paving contractor before parking heavy vehicles on a new surface.