How Do I Find Out the Formula for Asphalt Tonnage?

Measure the width, length and depth of the area to be paved.

Multiply the width by the length. Multiply this number by the depth. For a 12-foot by 20-foot driveway with a depth of six inches, the calculation would be: 12 x 20 = 240 x 0.5 = 120 cubic feet.

Multiply your answer by the weight, in pounds, of one cubic foot of asphalt. The weight used by the National Asphalt Pavement Association for estimating is 145 pounds per cubic foot. The calculation for this example would be: 120 x 145 = 17,400.

Convert your answer from pounds to tons by dividing it by 2,000. In the above example, 17,400 / 2,000 = 8.7. The " / " in this example represents the division operator.