Concrete Slab Volume Calculator
Calculate concrete slab volume in cubic metres from length, width and thickness for pour and order quantities, free in your browser.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the slab length, width and depth.
- Press Calculate for the volume in cubic metres.
How it works
The volume of a slab is length × width × depth, all in metres, giving cubic metres (m³).
Order a little extra to allow for uneven ground and spillage.
Worked example
4 m × 3 m × 0.1 m slab. Volume = 4 × 3 × 0.1 = 1.2 m³.
Common mistakes
- Entering the depth in millimetres while length and width are in metres — keep units consistent (100 mm = 0.1 m).
- Ordering the exact volume with no allowance — add ~10% for spillage and uneven ground.
Frequently asked questions
How do I calculate concrete for a slab?
Length × width × thickness gives cubic metres. A 4 × 3 m slab at 100 mm is 4 × 3 × 0.1 = 1.2 m³.
How much extra concrete should I order?
Add about 5–10% for spillage, uneven sub-base and over-dig; running short mid-pour is far worse than a small excess.
How many bags is that?
Use the Concrete Bags Calculator — roughly 0.01 m³ per 20 kg bag.
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Cite this tool
Zerdly. (2026). Concrete Slab Volume Calculator. Retrieved from https://www.zerdly.com/tools/concrete-slab-volume-calculator/
Tip: Enter any known values to calculate the remaining results.
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