One yard can cover different areas
A cubic yard contains 27 cubic feet. Spread those 27 cubic feet 4 inches thick and the coverage is 81 square feet. At 6 inches thick, the same volume covers 54 square feet. These are geometric results before an allowance or uneven ground.
The coverage formula is square feet = cubic yards × 324 ÷ thickness in inches. The reverse formula is cubic yards = square feet × thickness in inches ÷ 324. Keep thickness in inches throughout either formula.
Calculate a 240-square-foot project
For an area of 240 square feet at a specified 4-inch thickness, the net quantity is 240 × 4 ÷ 324 = approximately 2.963 cubic yards. At 6 inches, the same area needs approximately 4.444 yards. Area alone therefore cannot provide a meaningful concrete order.
If an irregular area has already been measured accurately in square feet, use the coverage calculator. For individual rectangular sections, the concrete calculator lets you work directly from dimensions. Measure deeper borders separately instead of applying their depth to the entire surface.
Keep price units consistent too
A supplier's dollars-per-cubic-yard rate and a contractor's dollars-per-square-foot installed rate describe different things. Multiply the supplier rate by purchased volume. Multiply the contractor rate by the area covered by that quote, then inspect its included scope.
For example, an illustrative $180 per cubic yard produces a material-only equivalent of about $2.22 per square foot at 4 inches before fees and allowance. That conversion does not include a crew, forms or site preparation. It cannot establish the fair installed price of a patio.
See comparing concrete quotes before choosing between offers with different units or inclusions. Retain both the net volume and your rounded order quantity in your notes.
Sources & further reading
Examples illustrate arithmetic. Use project specifications and current local supplier quotes for a purchase.