Concrete is a commonly used construction material that is normally sold by the cubic yard. There are 27 cubic feet in one cubic yard. Since most construction measurements are calculated in feet, you will need to convert the cubic footage measurement of the area where you want to pour concrete into cubic yardage. By performing this conversion and allowing for variances in measurements and waste, you can determine the number of cubic yards of concrete you need to order.
Measure the area where you want to pour the concrete with the tape measure. Area is three-dimensional, so measure the length, width and depth of the area. Alternatively, you can find measurement information on the architectural plans for the construction project. To calculate the cubic area, multiply the length times the width times the height. For example, assume you want to build a concrete wall. The projected wall measurements are 20 feet wide by 15 feet tall by 1 foot deep. Figuring the cubic area, 20 x 15 x 1 = 300 feet cubed. This figure represents the volume of the area where you want to pour the concrete.
Calculate the yards of concrete based on the projected measurements. There are 27 cubic feet in one cubic yard of concrete. Therefore, to calculate the cubic yards of concrete, divide the measurement of the area in cubic feet by 27. Continuing the same example, 300 / 27 = 11.11 cubic yards of concrete.
Calculate the cubic yards of concrete you actually need to order. Projected measurements for concrete are almost never completely accurate due to construction variances. In addition, you need to allow for a small amount of waste when ordering concrete. To calculate the amount of concrete you need to order for a project, multiply the yards of concrete from Step 2 by 1.10 and round the result to the next whole number. Continuing the same example, 11.11 x 1.1 = 12.221. Round this number up to 13. You should, therefore, order 13 yards of concrete for this construction project.