Concrete calculator in m³ for slabs and footings
This concrete calculator works out how much concrete you need in cubic metres: length times width times thickness, times the number of identical parts. Use it for a slab, a pad footing or a rectangular column. Add waste and round the order up to your concrete plant’s delivery step.
How does the concrete calculator work?
The calculator multiplies the dimensions together and by the count, then adds waste. Enter every dimension in metres: a 100 mm slab is 0.1 m.
| What you calculate | Formula |
|---|---|
| Slab | length × width × thickness |
| Footings and columns | length × width × height × count |
| To order | volume × (1 + waste) |
What should you check before ordering concrete?
The strength and exposure class come from the structural drawings, not from the calculator. Put parts on lines of their own when they take a different concrete or are poured on different days. Formwork, reinforcement, pumping and curing are separate lines in the quote.
The formulas and a worked small slab are in the guide how much grout, adhesive and concrete do I need. The basics of measuring, such as measuring the finished structure rather than what you buy, are in the guide to material takeoff.
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Questions and answers
- How do you calculate how much concrete you need?
- Multiply the length, width and thickness in metres to get cubic metres. A 4 × 3 m slab that is 0.1 m thick needs 1.2 m³ of concrete before waste.
- How much concrete do you need per square metre?
- As many cubic metres as the slab is thick in metres: 0.1 m³ per square metre for a 100 mm slab and 0.08 m³ for an 80 mm slab.
- How much waste should you add to a concrete order?
- Waste depends on the formwork, how even the base is and how the concrete is placed. The best starting value is what you have measured on your own jobs. Then round the order up to the delivery step of the concrete plant.