Concrete Slab Volume
Calculator
Results
- Concrete volume (m³)
- 3.599999
- Volume including waste (m³)
- 3.78
- Volume (cubic yards)
- 4.944053
Construction results
| Concrete volume (m³) | 3.599999 |
| Volume including waste (m³) | 3.78 |
| Volume (cubic yards) | 4.944053 |
formula-map diagram
- Concrete volume (m³)
- 3.599999
- Volume including waste (m³)
- 3.78
- Volume (cubic yards)
- 4.944053
Formula breakdown
Formula
V = L × W × t, then V × (1 + waste ÷ 100)= 3.6
Note
Simplified model: results are quantity estimates only. They ignore openings, overlaps, cuts, site conditions and local building codes. Structural figures are not a substitute for a design by a qualified engineer.
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See all →Frequently asked questions
What inputs does this calculator need to compute concrete volume?+
It needs the slab's length, width, and thickness (depth). Volume is simply length × width × thickness, though thickness is usually entered in inches or centimetres while length and width are in feet or metres, so the calculator handles the unit conversion internally.
Why is slab thickness usually so much smaller a number than length and width, and does that matter?+
Thickness is typically just a few inches (commonly 4 in for a patio or walkway, 5-6 in for a driveway) versus length and width in feet, so it must be converted to the same linear unit before multiplying — forgetting this conversion is the most common manual calculation error and leads to wildly wrong volumes.
Why does the calculator usually show volume in cubic yards instead of cubic feet?+
Ready-mix concrete is sold and priced by the cubic yard in the US, so converting the raw cubic-feet result (length × width × thickness in feet) by dividing by 27 (since 1 cubic yard = 27 cubic feet) gives the number a concrete supplier will actually quote against.
Should I order exactly the calculated volume from the supplier?+
No — it's standard practice to add 5-10% extra to account for uneven subgrade, form deflection, spillage, and minor thickness variations. Ordering exactly the theoretical volume risks running short mid-pour, which is far more costly than having a small surplus.
Does the calculator account for a sloped or non-rectangular slab?+
The basic calculation assumes a uniform rectangular slab of constant thickness. For sloped, curved, or irregular slabs, break the area into rectangular sections and calculate each separately, or use an average thickness if the slope is minor, then sum the volumes.