Calculation methodology

The concrete calculator converts all dimensions to feet, calculates volume in cubic feet, and divides by 27 to report cubic yards.

Shape formulas

• Slab or rectangular footing: length × width × thickness
• Cylindrical footing: π × radius² × depth

Waste and rounding

The selected waste percentage is added after base volume is calculated. Bag quantities are rounded up to whole bags because partial bags cannot normally be purchased. Displayed values may be rounded for readability while calculations retain additional precision.

Prices and yields

Material cost uses the price entered by the visitor. Bag-yield and ready-mix estimates are planning values, so users should confirm current product yield, supplier minimums, fees, and local prices before purchasing.

Last reviewed: August 14, 2026.