Concrete is sold by the cubic yard, in one-quarter cubic yard increments. Concrete producers usually require a minimum purchase of one cubic yard as smaller batches are sometimes less consistent. All measurements should be converted to feet then multiplied, and finally, divided by 27. An example would be a patio measuring 10’ 6” long x 14’ 3” wide x 4” thick. The example would be calculated as: (10.5 x 14.25 x .33) ÷ 27 = 1.83 cubic yards. It is common to add ten or fifteen percent to small loads and five to ten percent to larger orders to compensate for subgrade settlement, uneven subgrade, spillage and waste. In the example given, adding fifteen percent would bring the total to 2.1 cubic yards. The total should then be rounded up to the nearest one-fourth cubic yard, or 2.25 cubic yards. Please see our yardage calculator on our home page for more information about concrete “yield.” You can also contact us for assistance.