One of the most important steps to build a concrete wall is to have enough material for the project. There is a standard formula used to determine how much concrete is needed; when in doubt, it is better to ask for a little more than you think you need your project.
Measures
Know the height, width and thickness of your wall to calculate the necessary amount of concrete. When the measurement is not an exact fraction of an inch, it is better to round up.
Calculation formula
Multiply the height, width and depth in feet. For example, if you want to make a wall of 6 feet (1.83 m) high, 10 feet (3.05 m) wide and 0.34 feet (about 4 inches or 10.16 cm) thick, multiplies these three numbers for a Total of 20.4 cubic feet (0.58 cubic meters). Concrete is sold in cubic yards, so you’ll need to divide the calculation by 27 (the number of cubic feet in a cubic yard). In the above example, you divide 20.4 by 27 for a total of 0.75 cubic yards (0.57 cubic meters).
Concrete Extra
Having calculated how many cubic yards of concrete is need, you should add between 5 and 10 percent bonus to your calculation. This ensures that sufficient concrete have if a spill or other errors generate a loss of material.