EngineerHub.orgHow to use this calculator
Select the shape, enter finished dimensions, and add an allowance for uneven excavation, spillage and over-ordering.
Inputs
Results
Background
Engineering basis, equations, assumptions, interpretation and practical limitations for this calculator.
Rectangular elements use length × width × thickness. Circular elements use π × diameter² ÷ 4 × height.
Actual demand can increase because of uneven subgrade, form movement, pump priming, spillage and rejected concrete. Discuss delivery increments and minimum order quantities with the supplier.
Frequently Asked Questions
Practical questions about assumptions, inputs, interpretation and limitations.
The appropriate allowance depends on geometry, excavation tolerance, spillage, formwork accuracy and placement method. Simple formed work may need only a modest allowance, while irregular excavations can require more.
No. Reinforcement volume is normally small compared with typical ordering and placement uncertainty, so it is not deducted in this calculator.
The mass estimate uses 2400 kg/m³ as a representative normal-weight concrete density. Actual density varies with aggregate type, air content and mix design.
One cubic yard equals 27 cubic feet. The calculator converts the same calculated physical volume between cubic metres, cubic feet and cubic yards.
Use it as a quantity estimate. Before ordering, confirm dimensions, drawing revisions, waste allowance, supplier minimum loads and any site-specific overbreak or placement losses.