Calculating cubic feet might be necessary to know how many cubic feet are in an area, such as when you are laying concrete and need to know how much mix to use. Finding cubic feet is similar to finding square footage, but with the added element of height. Instead of finding the number of feet in a flat area, you are finding volume by multiplying the length, width and height of a space in feet.
Use a tape measure to measure the length in feet of one side of the area of which you need to know the cubic footage. Length usually refers to the longer side. For example if you are finding cubic footage of a storage container, measure along one side of the container. For example, 20 feet.
Measure the width of the space. Width generally refers to the shorter side. For example, 5 feet 8 inches.
Measure the height of the space. Height refers to the distance from the floor to the ceiling of the container. For example, 7 feet 6 inches.
Convert the inches to decimals to make them easier to multiply. There are 12 inches in a foot, so divide the number of inches by 12 to get the decimal equivalent. In the example the container is 20 feet x 5.67 feet x 7.5 feet.
Multiply your length, width and height to find cubic feet. In the example, the container is 850.5 cubic feet.