Concrete Volume Calculator
Calculate concrete volume for a rectangular slab, footing, or pad.
Calculation example
Inputs: Length: 20 ft, Width: 10 ft, Thickness: 0.5 ft
Result: 100 cubic units
A 20 ft by 10 ft slab that is 0.5 ft thick needs 100 cubic feet of concrete.
Formula
Concrete volume = length × width × thickness.
How to use this calculator
Multiply length by width by thickness. Keep all dimensions in the same unit.
Before you calculate
Measure the project dimensions as accurately as practical and keep all measurements in compatible units. For material products, use the coverage, yield, density, or package size stated by the manufacturer or supplier rather than a generic assumption.
Choose the waste allowance based on the project shape, installation method, cutting requirements, and material characteristics. A simple rectangular estimate may need adjustment for openings, corners, slopes, joints, patterns, compaction, or other site conditions.
Understanding the result
The calculator provides a planning estimate based on the inputs shown above. It is not a substitute for project drawings, structural design, manufacturer instructions, or local requirements. Before ordering, compare the calculated quantity with the supplier's package sizes and ordering units.
Tips
- Measure the actual thickness at several points.
- Add a project-specific allowance for waste or uneven ground.
Frequently asked questions
What does this calculator estimate?
It estimates rectangular concrete volume from length, width and thickness.
What should I add beyond the calculated volume?
Allowances for waste, uneven subgrade and project conditions may be needed.
Related calculators
Use compatible units and verify estimates against project specifications, local requirements and manufacturer instructions.