Concrete Calculator
Estimate concrete volume for rectangular slabs, floors and footings.
Results
Required concrete volume
- Base volume
- 2 m³
- Waste amount
- 0.1 m³
This is a rectangular volume estimate. Actual order quantities can vary with site conditions, uneven surfaces, losses and placement methods. Confirm the allowance and order quantity for your project.
Formula · How it works
Formula
Base volume = Length × Width × Thickness × Quantity; Waste volume = Base volume × Waste% / 100; Required volume = Base volume + Waste volumeThe volume of one rectangular section is length × width × thickness. Multiply by quantity, then add base volume × waste percentage / 100. Dimensions are converted to a common unit before multiplication. One cubic meter is 1,000 liters; one cubic yard is 27 cubic feet.
Worked example
For one slab measuring 5 m × 4 m × 0.1 m, base volume is 2 m³. A 5% waste allowance adds 0.1 m³, giving 2.1 m³, or 2,100 L, of required concrete.
How it works
Use the depth of concrete you intend to place, not the total excavation depth. Quantity repeats the same dimensions; calculate sections with different dimensions separately and add their volumes. The waste allowance is added to the calculated geometric volume.
Common questions
How do I calculate concrete volume?
Multiply length by width by thickness using consistent units, then multiply by the number of identical sections. Add your chosen waste allowance to obtain the required volume.
How much extra concrete should I order?
Choose an allowance that reflects your dimensions, site conditions and placement method. The calculator starts at 5% as an editable example; it is not a universal ordering recommendation.
How do I convert cubic feet to cubic yards?
Divide cubic feet by 27 because one cubic yard contains 27 cubic feet. For example, 54 ft³ equals 2 yd³.
What is concrete waste allowance?
It is an extra volume added as a percentage of the base estimate to account for expected losses or variation. A 5% allowance on 2 m³ adds 0.1 m³. Enter zero if you only want the geometric volume.