To estimate the quantity of concrete required for simple projects such as slabs and paths.
Measure the length, width and depth of the slab or path in metres.
The volume in cubic metres (m³) is calculated by multiplying the length by the width by the depth.

When ordering concrete an overage is often included due to spills, uneven ground, excavation variances, and wastage.
A general guide that contractors use is 5% for formed elements and 10-15% for unformed elements. The amount of reinforcement included should also be considered.

EXAMPLE

Drive way slab is 4.5 m in length , 1.8 m in width, and 125 mm (0.125 m) deep.
Volume = 4.5 x 1.8 x 0.125 = 1.01 m³

Extra 10% = 0.10 m³, therefore the total volume needed = 1.01 + 0.10 = 1.11 m³