Asphalt Calculator
Work out how many tons of hot-mix asphalt a driveway, parking area or overlay needs from its area and compacted thickness, with waste and cost.
How to Use
- Pick the shape, or enter a known area if you have measured it already (for example with the Map Measuring Tool).
- Enter the compacted thickness, the depth after rolling, usually 2 to 3 inches for a driveway.
- Leave the density at 145 lb/ft³ unless your plant quotes another figure.
- Add a few percent for waste and uneven base, and a price per ton for the cost.
- Read the tons to order; Show Work lists every step.
Worked Example
A driveway 40 ft long and 12 ft wide, 3 in thick when compacted. Area = 40 × 12 = 480 ft². Thickness = 3 ÷ 12 = 0.25 ft, so the volume is 480 × 0.25 = 120 ft³. At 145 lb/ft³ that is 120 × 145 = 17,400 lb, and 17,400 ÷ 2,000 = 8.7 tons. With 5% for waste and low spots, order 9.1 tons.
The same job by the rule of thumb. 480 ft² is 53.3 yd². At about 110 lb per square yard per inch, 53.3 × 3 × 110 = 17,600 lb, 8.8 tons: close to the full calculation.
The common mistake: using the loose thickness. If the 3.75 in the paver lays is used instead of the 3 in after rolling, the order comes out 25% high: 10.9 tons instead of 8.7.
Show Work
Formulas
How Asphalt Paving Works
Hot-mix asphalt is about 95% crushed stone and sand held together by about 5% bitumen. It is mixed at 275–325 °F (135–165 °C), trucked to the site, spread by a paver and compacted by rollers while still hot; the rolling packs the stone tight and squeezes out air, which is why the density used for ordering is the compacted figure.
Asphalt is sold by the ton because plants weigh every truck on the way out. A good result depends more on the base than the blacktop: a firm, well-drained, compacted gravel base keeps the surface from cracking and rutting, and edges need support so they do not crumble.
About This Calculator
This calculator finds the tons of hot-mix asphalt for a rectangular or round area, or any area you know, at a compacted thickness and density you can change, with an allowance for waste and the cost per ton. It works in feet, inches and US tons, or in metres, centimetres and tonnes.
Everything runs in your browser; nothing is sent anywhere. Paving contractors and plants may use their own density for a given mix; use their figure when you have it.
Related calculators: Gravel Calculator, Concrete Calculator, and Paver Calculator.
Frequently Asked Questions
How many tons of asphalt do I need?
Multiply the area by the compacted thickness in feet to get cubic feet, then by the density, about 145 lb/ft³, and divide by 2,000. A 40×12 ft driveway 3 inches thick is 120 ft³, which is 17,400 lb or 8.7 tons.
How much area does a ton of asphalt cover?
At 145 lb/ft³ a ton is 13.8 ft³. Laid 2 inches thick it covers about 83 ft²; 3 inches, about 55 ft². The industry rule of thumb is about 110 lb per square yard per inch of thickness.
How thick should an asphalt driveway be?
Residential driveways are usually 2 to 3 inches of compacted hot mix over 6 to 8 inches of compacted gravel base. Parking lots and drives that carry trucks are thicker, often laid in two lifts: a base course and a surface course.
Is the thickness before or after compaction?
Use the compacted thickness. Hot mix loses roughly a quarter of its loose thickness under the roller, so the paver lays about 3.75 inches to finish at 3. Tonnage is based on the finished, compacted density, which is why the result already accounts for that.
What is the difference between asphalt, blacktop and tarmac?
In everyday use they mean the same thing: stone aggregate bound with bitumen (asphalt cement), laid hot and rolled. Tarmac originally meant tar-bound macadam, patented in Britain by Edgar Purnell Hooley in 1902; modern pavements use petroleum bitumen instead of coal tar.
How do I use the Asphalt Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Do I need to install or sign up for anything?
Not at all — it runs in the browser with nothing to install and no account. After it loads once, it even works without an internet connection.
Is my information private?
Yes. Everything happens in your browser. Nothing you type is sent to a server or saved anywhere.
Common Use Cases
Driveway
A 40×12 ft driveway 3 in thick: 8.7 tons, or 9.1 tons with 5% waste.
Parking area
A 60×40 ft lot 3 in thick is 600 ft³: 43.5 tons before waste.
Overlay
A 1.5 in overlay over 3,000 ft² of old pavement is 375 ft³, 27.2 tons.
Cul-de-sac
An 80 ft round turnaround 3 in thick covers 5,027 ft²: 91.1 tons.
Metric job
A 50 m² drive at 6 cm compacted is 3 m³, about 6.97 tonnes at 2,323 kg/m³.
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