How to Figure the Amount of Gravel Needed for a Driveway

Measure the estimated width of the driveway. For driveways that widen at the street or narrow at the garage door, choose a place to measure that is typical of the overall average width. Record this measurement as driveway dimension "A."

Measure the overall estimated length of the driveway and record this measurement as dimension "B."

Determine the area of the driveway by multiplying dimensions A and B. The product is the area of the driveway surface in square feet.

Calculate the volume of the driveway area in cubic feet. Multiply the area determined in Step 3 by the desired depth of the gravel. This defines the volume of the driveway in cubic feet. Note: the calculation must be done in the same units of measurement, so the depth in inches must be translated into feet. Divide the number of inches in depth by 12 to translate the number to feet. For example, a gravel depth of 2 inches equals .167 feet; a depth of 3 inches equals .25 feet; and a depth of 4 inches equals .334 feet.

Calculate the quantity of gravel needed into cubic yards. Gravel products are typically ordered in cubic yards. To translate the volume determined into cubic yards, the volume determined in Step 4 is divided by 27 to determine the cubic yards of gravel needed. For instance, for a driveway that is 16 feet wide, 40 feet long, with a gravel depth of 3 inches, the calculation is 16 times 40 equals 640 square feet of area. The area of 640 square feet times the depth of .25 feet equals a volume of 160 cubic feet. A driveway volume of 160 cubic feet divided by 27 equals 5.93 cubic yards of gravel needed.