Asphalt by the ton
Asphalt, or blacktop, is usually bought and priced by weight, but a driveway is measured by its length, width and thickness. Turning the one into the other needs the density of the mix, and a margin for an uneven base and waste.
This asphalt calculator works out the volume of your area, adds an allowance, and converts it to US tons and metric tonnes using a density you can change. Add a price per ton and it estimates the material cost.
How to use it
- Measure the length and width of the area. Split curved or L shaped drives into rectangles and add the results.
- Enter the thickness after rolling. Driveways are often laid a few inches thick; your contractor sets the right depth for the base and traffic.
- Keep the density at 145 lb per cubic foot, or use your supplier’s figure, and set an allowance for waste.
- Add the price per ton if you have a quote, and read the tons, volume and cost.
The asphalt formula
volume (cu ft) = length × width × thickness (in) ÷ 12 × (1 + allowance)
weight (lb) = volume × density; tons = lb ÷ 2,000
metric: tonnes = m³ × density (t per m³)A US ton is 2,000 lb; a metric tonne is 1,000 kg, about 2,205 lb. The default density of 145 lb per cubic foot is a typical estimate for compacted hot mix asphalt, about 2.32 tonnes per cubic metre. Mixes differ, so a supplier’s figure is always better.
Worked example: a 40 by 12 foot driveway, 3 inches thick
- Volume: 40 × 12 × 3 ÷ 12 = 120 cu ft
- With 5% extra: 126 cu ft
- Weight: 126 × 145 = 18,270 lb
- In tons: 18,270 ÷ 2,000 = 9.13 tons
- At $120 a ton: $1,096.20 for the asphalt
The driveway needs about 9.13 tons of asphalt, costing about $1,096.20 at $120 a ton. Labour, base preparation and delivery are extra.
Tons for some common areas
| Area | 2 inches thick | 3 inches thick |
|---|---|---|
| 20 × 10 ft | 2.42 tons | 3.63 tons |
| 40 × 12 ft | 5.8 tons | 8.7 tons |
| 60 × 20 ft | 14.5 tons | 21.75 tons |
Each extra inch of thickness adds half again to a 2 inch layer, so the depth you choose matters as much as the area.
Planning the job
- A firm, well drained base of compacted stone matters as much as the asphalt itself. The gravel calculator sizes the stone.
- Edges need support so they do not crumble.
- Hot asphalt must be laid and rolled quickly while it is still warm, so order a little extra rather than stopping halfway.
- For a concrete drive instead, see the concrete calculator.
Frequently asked questions
How many tons of asphalt do I need?
Multiply length by width in feet, then by the thickness in inches divided by 12, for cubic feet. Multiply by the density, often about 145 lb per cubic foot, and divide by 2,000 for tons. A 40 by 12 foot drive at 3 inches needs about 8.7 tons before any allowance.
How much does a cubic yard of asphalt weigh?
At a typical 145 lb per cubic foot, a cubic yard of compacted asphalt weighs about 3,915 lb, or roughly 1.96 tons. The exact figure depends on the mix and how well it is compacted, so suppliers may quote a slightly different weight for their product.
How thick should a driveway be?
Residential driveways are often laid a few inches thick over a compacted stone base, with heavier traffic needing more. The right thickness depends on the soil, the base and the vehicles using it, so take the figure from your contractor or local guidance and enter it above.
How do I estimate the cost of asphalt?
Work out the tons needed, then multiply by the price per ton from your supplier. Enter that price above to see the material cost. Remember that labour, base preparation, delivery and any old surface removal are usually priced separately, and can cost more than the asphalt itself.
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