How to estimate concrete
Measure the slab and add a waste allowance.
1
Measure length and width
Use the actual pour dimensions.
2
Set thickness
Convert centimetres to metres in the formula.
3
Add waste
Five percent is typical for a simple slab.
What does this tool do?
Concrete is ordered by volume. This calculator multiplies length, width and thickness, adds a waste allowance, and converts the result into cubic metres, cubic yards and 80 lb bags.
The Formula
Volume = Length × Width × ThicknessFrequently Asked Questions
How thick should a concrete slab be?
A garden path may be 7–10 cm; a shed base often 10–15 cm; vehicle areas need more and should be engineered. Local codes vary.
How many 80 lb bags make a cubic metre?
A rough rule is about 59 bags per cubic metre, but yield depends on the mix. Confirm with the supplier.