Convert length, width, and depth into cubic yards so you can order the right amount of concrete or cement mix.
Overview
Concrete orders are sold by the cubic yard. Measuring a slab or footing in feet and inches and converting correctly prevents short loads and expensive second trips.
This calculator multiplies length and width in feet by depth in inches converted to feet, then divides by 27 to report cubic yards.
Add a waste factor on site—typically 5–10%—for uneven grade, spillage, and form variation before you place an order.
Steps
Enter the pour length in feet.
Enter the pour width in feet.
Enter slab or footing thickness in inches.
Review cubic feet and cubic yards.
Increase the order slightly for waste and over-excavation.
Math
cuFt = lengthFt × widthFt × (depthIn / 12); cuYd = cuFt / 27
Volume is area times thickness. Dividing cubic feet by 27 yields cubic yards used by ready-mix yards.
Worked cases
10×10×(4/12)=33.33 cu ft; 33.33/27≈1.23 cu yd
About 1.23 cubic yards before waste.
20×12×(5/12)=100 cu ft; 100/27≈3.70 cu yd
About 3.7 cubic yards.
8×2×1=16 cu ft; 16/27≈0.59 cu yd
About 0.59 cubic yards.
Why use this
Questions