Construction calculator
Concrete Calculator
Estimate concrete volume for slabs, footings, walls and round pads in cubic yards or cubic metres.
Enter dimensions and calculate.
Concrete slab example
Example: 20 ft × 12 ft slab, 4 in thick, with 10% waste allowance.
20 × 12 × (4 ÷ 12) = 80 ft³
80 ÷ 27 = 2.96 yd³
2.96 × 1.10 = 3.26 yd³ to order
80 ÷ 27 = 2.96 yd³
2.96 × 1.10 = 3.26 yd³ to order
How much extra concrete should I order?
A waste or overage allowance helps cover uneven excavation, form movement, spillage and small measurement errors. The right allowance depends on the project. Enter the percentage you want rather than relying on a fixed assumption.
Metric and imperial concrete calculations
Metric users can enter metres and centimetres and receive cubic metres. Imperial users can enter feet and inches and receive cubic yards. The calculator also shows the converted equivalent for easier comparison with supplier quotes.