Concrete Calculator - Estimate Volume, Bags & Cost
Calculate the volume, number of pre-mix bags, and total cost of concrete needed for slabs, footings, or columns. Includes wastage factor.
Project Details
How to Use This Calculator
Start by picking the shape of your pour and the unit system that matches your plans. Slab inputs show length, width, and depth; column inputs show diameter and height. Controls to the right explain the current unit labels.
- Select Shape and Units: Choose slab or column and toggle between Imperial and Metric. Labels update so you always know whether to enter feet, inches, or meters.
- Enter Dimensions: Type the measured length, width, depth, diameter, or height. Small validation marks keep the calculator from running with missing numbers.
- Add Wastage and Bag Details: Apply a 5–10% buffer for spill or overpour, pick your pre-mix bag size, and enter the cost per cubic yard or meter.
- Review Results: The right column shows base volume, total volume with wastage, the number of bags to buy, and the total material cost.
Methodology
The calculator uses classical geometric formulas for rectangular prisms and cylinders, then adds the user-supplied wastage percentage before dividing by the chosen bag volume. All volumes stay in their native units (cu ft or m³) until the final display, where Imperial results convert to cubic yards for comparison with supplier pricing.
Bag counts always round up so you order enough material, and costs multiply the total volume by the per-unit price you enter. Results are estimates; double-check with your supplier and local building code before purchasing.