Concrete is a building material most commonly sold in cubic yards. There are 27 feet in a cubic yard. Since many construction measures are calculated in feet, you need to convert the area you want the concrete poured into cubic measurement. When making this conversion, allow for variations in measurements and waste, and you can determine the number of cubic yards of concrete you need order.
- With your tape measure, measure the area where you want to pour concrete. The area is three-dimensional, so measure the length, width and depth of the area. Alternatively, you can find this information on the architectural plans of the construction project. To calculate the cubic area, multiply the length by width by height. For example, suppose you want to build a concrete wall. Measurements of the wall are 20 feet wide by 15 feet high by a foot deep. Calculate the cubic area, 20 x 15 x 1 = 300 cubic feet. This figure represents the volume of the area where you want to pour concrete.
- Calculate yards of concrete base on the planned measurements and knowing that there are 27 cubic feet in a cubic yard of concrete. Therefore, to calculate the cubic yards of concrete, divide the measured area in feet by 27. Using the same example as above, 300/27 = 11.11 cubic yards of concrete.
- Proposed measures for concrete are almost never completely accurate due to variations in construction. In addition, you need to allow for a small amount of wasted concrete. To calculate the total amount of concrete you need for the project, multiply the amount of cubic yards from step 2 by 1.10 and round the result to the next whole number. Following the same example, 11.11 x 1.1 = 12.221. Round this number up to 13 so you must order 13 yards of concrete for this construction project.