When beginning a task involving concrete, you will need to determine the amount of concrete needed to complete the task. Concrete is generally delivered in cubic yards, so when ordering you will need to know how many cubic yards to purchase. Properly calculating a cubic yard of concrete in quite easy, but it is also extremely important.
A cubic yard of concrete measures 36-by-36-by-36 inches, or 36 inches cubed. Multiply these numbers (36 x 36 x 36) to determine the cubic inches in a cubic yard (46,656).
Measure the amount of area you will need to concrete and record the measurements in inches.
Multiple these numbers to determine the amount of concrete needed. (Example: A 4-by-36-by-240-inch sidewalk would need 34,560 cubic inches.)
Divide the amount of concrete needed (34,560) by the cubic inches in a yard of concrete (46,656).
The calculation should look like this. 34,560 divided by 46,656 equals 0.74 cubic yards needed to complete this project.