Concrete Calculator
Find the concrete volume and assumed material cost for a rectangular slab. Add an allowance without changing the measured dimensions.
Your result
- Concrete including allowance
- 2.2 m³
- Geometric volume
- 2 m³
- Estimated concrete cost
- $330.00
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Formula
Geometric volume = length × width × depth; order volume = geometric volume × (1 + allowance ÷ 100).
Worked example
The initial example uses the following assumptions. Its result is computed by the same engine as the calculator. Measurements are metric and money amounts use USD; these are illustrative inputs, not market prices.
- Room length
- 5 m
- Room width
- 4 m
- Slab depth
- 10 cm
- Waste allowance (%)
- 10
- Concrete price
- 150 per m³
- Concrete including allowance: 2.2 m³
- Geometric volume: 2 m³
- Estimated concrete cost: $330.00
Assumptions and limitations
This estimates quantity, not structural safety. Ground conditions, compaction, formwork, reinforcement, delivery minimums and supplier rounding need separate assessment.
Questions about this calculation
Why is order volume higher than slab volume?
The allowance is the extra quantity you choose for practical variation. It is not a structural safety factor.
Can this design a foundation?
No. It can estimate a rectangular volume but cannot specify a safe foundation or its reinforcement.
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