How much asphalt (tarmac) do I need for a driveway?
Published · Updated · By Sai Nath
Tonnes = length × width × compacted thickness (all in metres) × density ÷ 1,000. Then add about 10 percent. A 10 m × 3 m driveway laid 50 mm thick is 1.5 m³. At an example density of 2,400 kg/m³ that is 3.6 tonnes, or about 4 with the allowance. Ask your supplier for their density and thickness.
How do I work out how much asphalt I need?
- Measure the area. Length × width in metres. For an odd shape, split it into rectangles and add them. If you start from an area, see square metres to cubic metres.
- Pick the finished, compacted thickness. Work in metres: 50 mm is 0.05 m. This is the thickness after the roller, not the loose depth the paver lays.
- Find the volume. Area × thickness = cubic metres. The arithmetic is in how to calculate cubic metres.
- Convert to tonnes. Cubic metres × density (kg/m³) ÷ 1,000. One tonne is 1,000 kg (NIST SP 811, Appendix B.8; checked on 28 October 2026).
- Add an allowance. About 10 percent is a common rule of thumb for edges, uneven ground and the ends of a load. It is not a standard.
A worked example: a 10 m × 3 m driveway at 50 mm
Say the supplier's compacted density is 2,400 kg/m³. That is the figure MeisterCalc starts with. It is an app default, not a standard and not a supplier's figure, so treat it as an example.
- Area: 10 × 3 = 30 m².
- Volume at 50 mm: 30 × 0.05 = 1.5 m³.
- Weight: 1.5 × 2,400 ÷ 1,000 = 3.6 t.
- With 10 percent on top: 3.6 × 1.10 = 3.96 t. Ring the contractor with "about 4 tonnes" and ask how they quote it.
How many tonnes of asphalt per square metre?
Per square metre the answer depends only on thickness and density: tonnes per m² = thickness in metres × density ÷ 1,000. At the same example 2,400 kg/m³:
| Compacted thickness | Tonnes per m² | 10 m² needs |
|---|---|---|
| 25 mm | 0.06 t | 0.6 t |
| 30 mm | 0.072 t | 0.72 t |
| 40 mm | 0.096 t | 0.96 t |
| 50 mm | 0.12 t | 1.2 t |
| 75 mm | 0.18 t | 1.8 t |
Worked sums for the 40 mm row: 0.04 × 2,400 ÷ 1,000 = 0.096 t per m², and 10 × 0.096 = 0.96 t for 10 m². These thicknesses show the arithmetic only. They are not recommendations. If your supplier's density is 2,300, scale the figures by 2,300 ÷ 2,400, about 4 percent fewer tonnes: on the 30 m² job at 50 mm, 1.5 × 2,300 ÷ 1,000 = 3.45 t instead of 3.6 t. The 2,300 is made up to show the effect.
Asphalt, tarmac, blacktop and bitumen: is it the same sum?
Mostly, yes. Asphalt, tarmac and blacktop are regional names for much the same material: asphalt is common in Australia and New Zealand, tarmac in the UK, blacktop in the US. Whatever the name, the sum for a hot-laid surface is area × compacted thickness × density. Bitumen is the binder inside the mix, not the finished surface. Cold-lay tarmac sold in bags is a different product with its own coverage on the bag, so use the bag's figures, not this sum.
How thick should asphalt be for a driveway?
This page gives no thickness, because the right figure depends on the ground, the traffic and the mix. Take it from your contractor's specification or your council, write it down, and use that number in the sum above. A few things the maths does not tell you: a driveway for cars and one for trucks are not the same job, and the asphalt may be laid in more than one course, so work each course with its own thickness and density, then add them. As an example at the same 2,400 kg/m³ over the 30 m² drive: a 30 mm course is 30 × 0.03 × 2,400 ÷ 1,000 = 2.16 t and a 20 mm course is 30 × 0.02 × 2,400 ÷ 1,000 = 1.44 t, which add to 3.6 t.
Does the base count, and why does it matter more than the maths?
The base under the asphalt is a separate material with its own tonnes, so it is not in the asphalt sum. It matters more because asphalt only spreads the load: if the ground and the compacted base under it move, the surface cracks whatever the tonnage. Work the base out on its own with how much road base do I need, or how much gravel do I need if your base is gravel. The base depth, like the asphalt thickness, comes from your contractor or council. The fall of the finished surface matters too; see driveway gradient.
Why does the density come from the supplier?
Asphalt mixes differ, and the density that matters is the compacted one for the exact mix you are buying. Two questions get you the number: "What is the compacted tonnes per cubic metre?" and "Is that for the mix you are quoting?" So this page gives no density as fact. For the tonnes and cubic metres conversion in both directions, see cubic metres to tonnes.
Why order a little over the calculated figure?
Edges are never perfectly even, the base below is never perfectly flat, and a load rarely ends exactly where the job does. About 10 percent covers the usual shortfall. MeisterCalc builds in the same 10 percent as Order (+10%). It is a flat allowance, not a compaction factor. Contractors often quote by area and thickness and look after the ordering themselves, so confirm who is responsible for the tonnage.
Doing it in MeisterCalc
- Open MeisterCalc and tap Asphalt on the home screen (Home ▸ Asphalt).
- Enter Length, Width and the compacted Depth. Millimetres are the default; feet and inches are under Settings ▸ Units ▸ Default units.
- Check Density (kg/m³). The app starts at 2,400, which is an app default and not a supplier figure. Type in your supplier's compacted figure.
- Read Volume (m³), Weight (t) and Order (+10%) (t).
- Optional: enter a Price per tonne. A wastage slider then appears, starting at 10 percent, with Total Cost and Cost + N% Waste rows. Use Share results for text or PDF.
For the example, entering 10 m, 3 m, 50 mm and a density of 2,400 should give Volume 1.500 m³, Weight 3.600 t and Order (+10%) 3.960 t.
What the calculator doesn't do
- No compaction setting. Enter the compacted thickness and the compacted density instead.
- One layer at a time. For two courses, run it twice and add the results.
- No base or sub-base calculation, and no thickness presets for driveways or paths.
- It is not a cold-lay or bagged tarmac calculator.
- The 10 percent is a flat rule of thumb. Density must be between 100 and 5,000 kg/m³.
- It does not know the thickness your site, contractor or council requires.
Try it
Concrete, Stairs and Check Square are the free calculators. Asphalt is among the other twelve, which unlock with a weekly subscription that starts with a 3-day free trial, or with a one-time lifetime unlock; Google Play shows the prices in your currency. Calculations work offline, on Android 7.0 or later. There's no iPhone version yet; you can join the iOS waitlist.
Sources
- NIST Guide to the SI, Appendix B.8: tonne = 1,000 kg. Checked on 28 October 2026.