The core formula
Every calculator finds a volume in cubic feet and divides by 27. A cubic yard is 3 feet by 3 feet by 3 feet, so it holds 27 cubic feet.
cubic yards = cubic feet ÷ 27
Shape formulas
| Shape | Formula |
|---|---|
| Rectangle | Length × Width × Depth ÷ 27 |
| Circle | 3.1416 × (Diameter ÷ 2)² × Depth ÷ 27 |
| Cylinder | 3.1416 × (Diameter ÷ 2)² × Height ÷ 27 |
| Triangle | ½ × Base × Height × Depth ÷ 27 |
| Trapezoid | ((Short side + Long side) ÷ 2) × Height × Depth ÷ 27 |
| Oval | 3.1416 × (Length ÷ 2) × (Width ÷ 2) × Depth ÷ 27 |
| Cone | ⅓ × 3.1416 × (Diameter ÷ 2)² × Height ÷ 27 |
| Pile | ⅓ × 3.1416 × (Base diameter ÷ 2)² × Height ÷ 27 |
| Trench | Length × Width × Depth ÷ 27 |
| L Shape | ((Length 1 × Width 1) + (Length 2 × Width 2)) × Depth ÷ 27 |
| Sloped Area | Length × Width × ((Depth at start + Depth at end) ÷ 2) ÷ 27 |
| Irregular Area | Total area × Average depth ÷ 27 |
Units
Feet, inches, yards, meters, and centimeters are converted to feet before the math. One meter is 3.2808 feet, and one cubic yard is 0.7646 cubic meters.
Weights and bags
Weights use planning densities in pounds per cubic yard. Real material varies, so confirm with your supplier. Bag counts divide the order volume by the typical yield of each bag.
Waste
The waste setting adds a percentage to the final volume. Five to ten percent is common.