Plan a slab, patio, driveway or pad from finished dimensions. The result includes a user-controlled waste allowance and whole 60 lb bag estimate.
Results use your measurements and editable assumptions. Verify product coverage, density, waste and order rounding with the supplier before purchasing.
Volume = length × width × depth. Cubic yards = cubic feet ÷ 27.
BuildCalc converts measurements to a consistent internal unit, applies your project geometry and only then adds the selected waste allowance. Packaging quantities are rounded up because partial bags, blocks or boxes usually cannot be ordered.
Use this calculator when the pour can be represented as one or more rectangular sections. Measure the finished length and width, enter the specified concrete thickness, and calculate separate sections for steps, thickened edges or grade beams. The waste control is applied after the geometric volume so you can see the base quantity before adding an allowance.
A 12 ft by 20 ft slab at 4 in thick contains 80 cubic feet, or about 2.96 cubic yards, before waste. With a 10% allowance, the planning quantity is about 3.26 cubic yards. A ready-mix supplier may round that amount or apply a minimum order.
One cubic yard contains 27 cubic feet. Divide cubic feet by 27 to convert the geometric volume to cubic yards.
No. It estimates concrete volume only. Gravel base, reinforcement, forms, labor, delivery charges and structural requirements must be planned separately.
Published and maintained by EasyTool.me. Review the calculation methodology, verify product-specific values with the supplier, and report reproducible corrections. Last materially reviewed August 16, 2026.