Concrete volume formulas
Rectangular volume is length × width × depth. Circular and cylindrical volume is π × radius² × depth. The calculation uses a consistent internal unit, then reports only the measurement system you selected. Use the separate unit converter when a deliberate cross-system conversion is needed.
circular volume = π × (diameter ÷ 2)² × D
Worked concrete slab example
An 8.0 m long × 5.0 m wide slab poured 150 mm deep requires 8 × 5 × 0.15 = 6.00 cubic metres of concrete before waste. Adding a 7.5% allowance gives an estimated order quantity of 6.45 m³. This allowance is only an example; confirm formed dimensions, subgrade tolerance, supplier minimums and the project pour plan.
Waste allowance
The order volume adds the chosen percentage to the geometric net volume. The appropriate allowance depends on formwork accuracy, subgrade variation, pump priming, spillage, minimum order and supplier policy.
Bag yield
Pre-mixed bag products state an approximate mixed yield. Enter the printed yield in litres per bag in Metric mode or cubic feet per bag in US customary mode rather than assuming every bag size and mix produces the same volume.
Frequently asked questions
Can I use feet and inches?
Yes. Choose US customary to enter length and diameter in feet and depth in inches. Results remain in cubic yards and cubic feet.
Does the concrete result mix measurement systems?
No. Choose Metric or US customary and the inputs, result panel, printed report and CSV export stay in that system. Use the Construction Unit Converter for intentional conversions.
Why are truck equivalents only illustrative?
Actual mixer capacity, supplier minimums, access and load restrictions vary. Confirm the booked truck capacity with the supplier.