Asphalt Tonnage Calculator

About the Asphalt Tonnage Calculator

Asphalt plants sell hot-mix asphalt by the ton, weighed on a scale as each truck leaves the yard. Paving plans, on the other hand, are drawn in feet and inches. Turning one into the other is the first step in any paving estimate, whether it is a residential driveway, a parking lot, a farm road or a patch on a street. Order too little and the crew runs out mid-job, leaving a cold joint; order too much and you pay for asphalt that hardens in the truck.

This asphalt tonnage calculator converts the area and compacted thickness of a pavement into tons of hot mix. It also shows the area in square yards, the spread rate in pounds per square yard, how many 20-ton trucks the job needs and, if you enter a price, the cost of the material.

How to Use the Asphalt Tonnage Calculator

Enter the length and width in feet.

Enter the compacted thickness in inches.

Leave the density at 145 lb/ft³ unless your supplier gives a different figure, and optionally enter the price per ton.

The Formulas

  area        = length × width
  volume      = area × thickness ÷ 12
  tons        = volume × density ÷ 2,000
  square yards = area ÷ 9
  spread rate = tons × 2,000 ÷ square yards

Step-by-Step Example

A 60 × 12 ft driveway, 3 inches thick, at $100 a ton.

  area     60 × 12 = 720 ft² = 80 yd²
  volume   720 × 3 ÷ 12 = 180 ft³
  weight   180 × 145 = 26,100 lb = 13.05 tons
  rate     26,100 ÷ 80 = 326 lb/yd², about 109 per inch
  cost     13.05 × $100 = $1,305

Density of Hot-Mix Asphalt

Hot-mix asphalt is about 95% stone and sand by weight, held together by about 5% bitumen binder. Once rolled it typically weighs 140 to 150 pounds per cubic foot, and 145 is a common planning figure. That works out to roughly 110 pounds per square yard for each inch of thickness, a rule of thumb paving crews use constantly. Mixes with heavier stone, such as trap rock, weigh a little more; open-graded and porous mixes weigh less. If your contract gives a job mix formula, use its density.

Choosing the Thickness

Thickness depends on the traffic and the base. A residential driveway carrying cars usually needs 2 to 3 inches of compacted asphalt over 4 to 8 inches of compacted stone. Driveways used by delivery trucks, recreational vehicles or heavy equipment need more. Parking lots typically use 3 to 4 inches, often in two layers: a coarser base or binder course and a finer surface course. Roads are designed by engineers and may use 6 inches or more of asphalt over a thick base.

Ordering and Waste

Real bases are never perfectly flat, so low spots take extra mix. Edges are trimmed, and a little asphalt is always left in the truck bed and the paver hopper. Most contractors order 5 to 10% more than the calculated tonnage. Hot mix must be laid and compacted while it is still hot, usually above about 185 °F, so it cannot be stored for later. Schedule trucks so the paver never waits long and no load sits cooling.

Truckloads

Asphalt is hauled in insulated or tarped dump trucks. Tandem trucks commonly carry 15 to 20 tons, and larger trucks more. The calculator rounds up to 20-ton loads, which is a common planning size. For small jobs, a plant may have a minimum order or charge a small-load fee, and some suppliers sell cold patch or warm-mix asphalt in bags for repairs.

Irregular Areas

Few paved areas are perfect rectangles. Driveways flare at the street, parking lots have islands, and paths curve. Split the area into rectangles and triangles, work out each one's area, and add them together before calculating. For a curved drive, measure the length along the centre line and multiply by the average width. A turning circle or a round cul-de-sac is π × radius² in area. Taking a few extra measurements is quicker than finding out on the day that the asphalt has run short.

Base and Surface Courses

Thicker pavements are laid in two or more lifts, because a single thick layer is hard to compact evenly. The lower base or binder course uses larger stone and is laid first; the surface course uses finer stone for a smooth, tight finish. Each course is often a different mix with its own price per ton. Run the calculator once for each course using its own thickness, then add the tonnages and costs together.

Weather and Timing

Hot mix needs warm, dry conditions. Most specifications require air and ground temperatures of at least about 40 to 50 °F and rising, with no rain. In cold weather the mix cools before it can be compacted, leaving a weak, porous surface that soon breaks up. Plants often close for the winter in cold climates, so plan paving for late spring through early autumn.

Understanding Your Result

The headline gives the tons of hot-mix asphalt.

The weight line shows the area, volume and pounds.

The spread rate line gives square yards, pounds per square yard and the number of trucks.

The cost line multiplies the tons by your price.

When Should You Use This Calculator?

Use it when ordering asphalt for a driveway, lot or road.

Use it to check a contractor's tonnage on a quote.

Use it to compare the cost of different thicknesses.

Common Mistakes

Using loose instead of compacted thickness. Order by the finished, rolled thickness.

Forgetting waste. Add 5 to 10%.

Mixing up square feet and square yards. A square yard is 9 square feet.

Laying too thin. Thin asphalt cracks under loads.