How to use the asphalt calculator
- Enter the length and width of the paved area in feet, or switch to Total area if you already know the square footage. For an odd shape, add up the areas of its parts.
- Enter the thickness after compaction in inches. Use the figure your contractor or plan specifies.
- Check the weight of the compacted mix in pounds per cubic foot. The default is an example, so replace it with your supplier's number.
- Add an extra percent for uneven ground or spillage if you want one, and optionally a price per ton. Read the tons and the rounded-up quantity to order.
Formula
Volume (cu ft) = area (sq ft) x thickness (in) / 12
Weight (lb) = volume x extra factor x weight per cubic foot
Tons = pounds / 2,000
Cubic yards = cubic feet / 27
A ton here means a US ton of 2,000 pounds. Metric tonnes are shown as well, using 1 pound = 0.45359237 kilograms exactly.
A 40 by 25 foot driveway at 2 inches
The area is 40 x 25 = 1,000 sq ft. At 2 inches the volume is 1,000 x 2 / 12 = 166.67 cu ft, which is 6.17 cu yd. At 145 lb per cubic foot the weight is 166.67 x 145 = 24,167 lb, or 12.08 tons. In metric that is 10.96 tonnes. Rounded up to a tenth, order 12.1 tons.
With a 10 percent allowance the volume becomes 183.33 cu ft and the weight 13.29 tons. A 20 by 10 foot pad at 3 inches and 150 lb per cubic foot is 50 cu ft, 7,500 lb or 3.75 tons. At a price of $100 a ton, the 12.08 tons would cost $1,208.33.
Compacted thickness and weight
Asphalt is placed loose and then rolled, so it ends thinner than it starts. The thickness you enter should be the finished layer. The weight per cubic foot should likewise be the compacted weight. Mixes differ in stone, binder and air content, which is why the default of 145 pounds per cubic foot is only an example.
Ask your supplier for the compacted weight of the mix and for the thickness the mix needs. Many suppliers quote tons directly from area and depth, and this tool lets you check that quote.
What the estimate leaves out
The calculator covers the surface layer only. It does not include the base of crushed stone beneath it, tack coat, edging, grading or delivery minimums. A small area may cost more per ton because suppliers set a minimum load, so compare their price with your estimate.
For the stone base and fill, use the mulch and gravel calculator or the excavation volume calculator. For other paving materials see the concrete calculator and the paver calculator.
Assumptions and limits
- The area is flat and of even thickness, and the thickness is the compacted depth.
- The weight per cubic foot is an example value unless you replace it.
- A ton is 2,000 pounds. Tonnes use 0.45359237 kilograms per pound.
- The extra percent is optional and starts at zero. Some people add 5 to 10 percent, but that is your choice.
Frequently asked questions
How much asphalt do I need for a driveway?
Multiply the area in square feet by the thickness in inches, divide by 12 for cubic feet, multiply by the weight per cubic foot and divide by 2,000 for tons. A 1,000 square foot driveway at 2 inches and 145 pounds per cubic foot needs about 12.08 tons.
How many square feet does a ton of asphalt cover?
It depends on thickness and density. At 145 pounds per cubic foot, one ton covers about 82.8 square feet at 2 inches deep, since 2,000 pounds is 13.79 cubic feet and 13.79 x 12 / 2 is 82.8.
What weight should I use for asphalt?
Use the compacted weight your supplier gives for the mix. The tool starts with 145 pounds per cubic foot as an example only, and you can change it.
Should I add extra for waste?
That is up to you. The extra percent starts at zero, and you can add some for uneven ground, spillage or a thicker first lift. Your supplier can tell you what is usual for the job.