Concrete Floor Slab Calculator

Estimate concrete for a floor slab with live volume, waste, bags, cost, formula steps, and a branded report with a 3D measurement diagram.

Measurement inputs

Enter slab size. Results update live as you type.

Live calculation

Project name Used in saved reports and PDF.

Unit system Switches starter units only.

Length

Enter a length greater than 0.

Width

Enter a width greater than 0.

Thickness

Enter a thickness greater than 0.

Waste (%) Use 5%, 10%, or 15%. Waste cannot be negative.

Cost per cubic yard Optional. Leave as 0 if not needed. Cost cannot be negative.

Bag estimate based on Default uses waste volume.

Volumes are rounded to 2 decimals. Bags are rounded up.

Order quantity with waste

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Enter valid measurements to calculate concrete.

Base volume —

Cubic feet —

Cubic meters —

Estimated cost —

60 lb bags

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80 lb bags

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Floor area

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Thickness

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This estimate is for a rectangular concrete floor slab. Final order quantity should be checked with your concrete supplier or contractor.

The same formula and steps are saved in the report.

Rectangular floor slab volume

Volume = Length × Width × Thickness

All measurements are converted to feet before calculation.