How to Estimate the Concrete Needed for a Project

Before you begin any project that requires concrete, you must know exactly how much material you need. The last thing you want is to get halfway through constructing a sidewalk or driveway only to run out of concrete. Luckily, a standard method will help you estimate the amount of concrete you need for a project, and you'll typically order the concrete in cubic yards.

• 1

  Determine the length, width and depth of the area you'll fill with concrete in terms of feet. For example, you might want create a patio that is 30 feet long, 20 feet wide and .25 feet (3 inches) deep.

• 2

  Multiply the length, width and depth to determine the total area. In the above example, you would multiply 30 X 20 X .25 with the result of 150.

• 3

  Take the calculation of the area and divide it by 27 to determine the cubic yardage needed. For example, in the above patio, you would take 150 and divide it by 27 to get a total of 5.5 cubic yards.

• 4

  Add an extra 5% to your calculations to account for any spillage or other mistakes that may result in a loss of concrete. To build the above patio, you would need at least 5.8 (5.5 + 5%) cubic yards of concrete.