Concrete volume calculator

Formula

How it works

Volume is length × width × thickness. Add an allowance for spillage and uneven ground and order the larger figure.

Worked example

The same calculation with the default values:

• Length 6 m
• Width 4 m
• Thickness 10 cm
• Waste allowance 10 %

1. thickness = 10 cm ÷ 100 = 0.1 m
2. volume = 6 × 4 × 0.1 = 2.4 m³
3. with waste = 2.4 × (1 + 10 ÷ 100) = 2.64 m³
4. 2.64 m³ × 1.30795 = 3.45299 yd³

Result: Volume (no waste): 2.4 m³ · Volume to order: 2.64 m³ · Volume to order (cubic yards): 3.45298963 yd³

Common mistakes

• Forgetting to add a waste/overage allowance - concrete is always ordered with a margin (typically 5-10%) for spillage, uneven subgrade, and formwork variance; ordering the exact calculated volume often leaves a shortfall.
• Mixing up thickness units (entering centimeters where the field expects meters, or inches where it expects feet) - this error alone can throw the volume off by a factor of 100 or 12.
• Treating the calculated volume as exactly what will be delivered - ready-mix trucks and suppliers typically round up to their minimum order sizes, which may differ from the raw calculated figure.