Concrete Calculator
Calculate concrete volume for slabs, columns, tubes, curbs, and stairs in cubic yards and cubic feet. Estimate package count from the yield you enter and dry-mix weight from that count and the bag weight you enter.
Inputs and method
Choose a shape and enter its dimensions, quantity, waste allowance, yield per bag, and bag weight. Shape volume is calculated in cubic feet, waste is applied once, and bags are rounded up only after division by the entered yield. Estimated dry-mix weight is the exact rounded bag count multiplied by the entered bag weight.
Calculations retain full floating-point precision until the labeled display step. Counts and packages use an explicit upward ceiling only where a whole purchase unit is required.
Interpreting the estimate
Use the result as a planning value and keep input precision consistent with the measurements or source data you have. Small displayed differences can come from final-place rounding; intermediate values are not rounded.
Assumptions and limits
This is a geometric material estimate. The 0.6 cu ft yield and 80 lb weight shown initially are separate, editable planning assumptions. For metric cubic-meter quantities, use the concrete volume calculator; for masonry walls on top of the slab, see the brick calculator; and for concrete stair geometry, use the stair calculator. An 80 lb package does not have a universal yield: use the yield and weight printed for the product you plan to buy. The weight result is package count times entered package weight, not a concrete-density calculation. Product yield, subgrade, forms, spillage, reinforcement, placement, and structural requirements are separate.
Rejecting empty, invalid numeric, prohibited negative, zero-denominator, impossible, or unsupported inputs prevents the page from presenting a misleading numeric result.