Multiply figures for length, width and thickness, measured in feet, and divide by 27 to determine the yardage of concrete required. Multiply the total yards by 1.05 to allow for a margin of error to ensure enough materials are available. With a pocket calculator and tape measure, the process takes only a few minutes.Continue Reading
Use a tape measure to determine the size of the project. Enlist a helper to hold one end of the tape. Record the measurements in feet. Convert any inches over the full foot measure to a fraction of a foot by dividing the remaining inches by 12. Measure and record the dimensions of any areas that lie outside the larger rectangle in a similar method.
Convert the thickness of the concrete to a fraction of a foot. Calculate the volume by multiplying length by width by depth. Add any additional volumes from out of the main rectangle.
The volume figured using measurements in feet provides the number of cubic feet. Divide the volume by 27, the number of cubic feet in 1 cubic yard.
Multiply 1.05 by the number of cubic yards provided for over-excavation, spills and unforeseen events. Many concrete companies have a minimum load size or an additional charge for small loads, making it less expensive to have a small amount of materials left over than to have to order more concrete.