Estimate how much concrete you need for a slab, foundation, floor or other building project. Enter your dimensions using the units shown in the calculator to calculate the required concrete volume.
Check your measurements carefully, especially the depth or thickness, before calculating.
Enter your project measurements for a planning estimate. Rectangular volume only. Thickness must come from your project specification. All applicable wastage percentages are added to the net quantity. Whole packs, bags and pieces are rounded up. Planning estimate only. Confirm quantities, product specifications and rates with your supplier or contractor. This tool does not provide structural design or establish compliance with local building rules.Construction calculator
Concrete Calculator
Method & assumptions
For irregular areas, divide the project into smaller rectangular sections. Calculate each section separately, then add the volumes together.
For a rectangular slab or foundation:
Concrete volume = Length × Width × Depth
When all measurements are in metres, the result is in cubic metres (m³).
For example, a slab measuring 5 metres long × 4 metres wide × 0.1 metres thick requires:
5 × 4 × 0.1 = 2 m³ of concrete
This is the calculated volume before any additional allowance for site conditions or wastage. The example thickness illustrates the calculation; it is not a construction specification.
Your required quantity depends on the dimensions of the space being filled. Uneven excavation, changes in thickness, sloping ground and additional foundation sections can increase the volume.
Measure from the prepared base to the intended finished level. Account separately for thickened edges, beams, steps and other sections that differ from the main slab.
A cubic metre is a volume measuring one metre long, one metre wide and one metre deep. Concrete orders are commonly expressed in cubic metres.
Divide millimetres by 1,000. For example, 100 mm = 0.1 m and 150 mm = 0.15 m. Only convert manually if the calculator requires metres.
You may need an allowance for uneven ground, excavation variations and handling losses. Confirm a suitable amount with your contractor and supplier before ordering.
You can estimate the volume of rectangular foundation sections using their specified dimensions. Calculate sections separately without counting overlapping areas twice. Foundation dimensions must be determined for your project by a qualified professional.
A concrete volume result does not automatically provide a material breakdown. Separate quantities depend on the specified mix, material properties and batching method.
No. The calculator estimates volume from your measurements. It does not determine suitable thickness, concrete strength, reinforcement or structural requirements.
Explore our directory to find [building material suppliers](/suppliers/) and [contractors](/contractors/). Contact businesses directly to confirm concrete specifications, delivery arrangements, access requirements and quotations.
Results are estimates for preliminary planning. Actual requirements may vary with measurements, excavation, formwork, site conditions and handling losses. Confirm quantities and concrete specifications with your supplier or contractor before ordering. Structural requirements must be determined by a qualified professional.
