Enter values and select Calculate to see your result.
Estimate concrete volume and bags for a rectangular slab
Uses slab dimensions plus your waste allowance. Bag yield varies by product; use the manufacturer's stated mixed yield. Volume estimate only.
How to use the Concrete Calculator
Estimate concrete volume and material for a rectangular slab, footing or similar project.
- Enter length, width and depth in one unit.
- Choose waste or overage allowance when offered.
- Calculate estimated volume and material.
Concrete Calculator formula
Rectangular volume = length × width × depth; waste is applied after base volume.
Worked example
Inputs: A 10 ft by 12 ft slab that is 4 in deep.
What to expect: The tool converts depth and reports estimated slab volume.
How to read your result
Allow for uneven ground, spillage, formwork and supplier minimums before ordering.
Frequently asked questions
Why add extra concrete?
Pours can lose material to uneven excavation, spillage and measurement variation.
Can units be mixed?
Convert all dimensions to one unit first.