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Start with a realistic example, adjust the inputs, or save your numbers before experimenting.
A practical concrete volume scenario
For this example, use length of 5 m, width of 3 m, depth of 12 cm, waste allowance of 8 %, and yield per bag of 0.012 m³. These are starting values, so replace them with numbers that match your situation.
Length: 25% lower
Change length to 4 m while keeping the other example values the same.
Length: 25% higher
Change length to 6 m while keeping the other example values the same.
Interactive chart
See what changes the result
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Quick answer
What does the Concrete volume calculate?
How much concrete is needed for a slab or footing? This calculator uses length, width, depth, waste allowance, and yield per bag to estimate concrete volume immediately in your browser.
With the values currently entered, the result is 2.54 yd³ — concrete required. It also shows 80 l batches, bags at entered yield, and before waste.
How to use the Concrete volume
- Replace the example values with your own numbers.
- Review the result and supporting figures as they update automatically.
- Check the formula and assumptions before using the estimate for a decision.
Inputs used
- Length — entered in m
- Width — entered in m
- Depth — entered in cm
- Waste allowance — entered in %
- Yield per bag — entered in m³
Concrete volume formula
Length × width × depth × waste allowance
Assumptions
- The pour is a rectangular volume.
- Sub-base and reinforcement are excluded.
Practical guide
Concrete volume example and edge cases
How much concrete is needed for a slab or footing? Let's use a concrete example, then look at the assumptions that can move the answer.
Example: A practical concrete volume scenario
For this example, use length of 5 m, width of 3 m, depth of 12 cm, waste allowance of 8 %, and yield per bag of 0.012 m³. These are starting values, so replace them with numbers that match your situation.
- Length
- 5 m
- Width
- 3 m
- Depth
- 12 cm
- Waste allowance
- 8 %
- Yield per bag
- 0.012 m³
Calculated result2.54 yd³concrete required
Start with concrete required. Then check 80 l batches, bags at entered yield, and before waste to understand what sits behind the main result.
Example results use the default display profile. The calculator above follows your selected country and units.
How to read the result
- Read the main result first. The supporting figures for 80 l batches, bags at entered yield, and before waste explain how the estimate is built.
- The method is Length × width × depth × waste allowance. Keep the units consistent and use values from the same time period.
Edge cases worth checking
When length is unusual
The pour is a rectangular volume. Double-check this input before relying on the result.
When yield per bag is uncertain
Sub-base and reinforcement are excluded. Run a lower and higher value to see a useful range.
What changes the result most
Length
Measure length with the same unit shown beside the input. Convert first if your source uses another unit.
Width
Measure width with the same unit shown beside the input. Convert first if your source uses another unit.
Depth
Measure depth with the same unit shown beside the input. Convert first if your source uses another unit.
Try a different scenario
Small changes show whether the answer is stable or sensitive.
Length: 25% lower
4 m2.03 yd³concrete required
Length: 25% higher
6 m3.05 yd³concrete required
Width: 25% higher
4 m3.39 yd³concrete required
Common mistakes
Check length
The pour is a rectangular volume. Make sure this matches the number you enter.
Keep yield per bag consistent
Sub-base and reinforcement are excluded. Use the same units and time period throughout the calculation.
Do not rely on one concrete volume scenario
Run a cautious case and an optimistic case. The range is often more useful than one exact-looking number.
Use this result well
How much concrete is needed for a slab or footing?
Confirm measurements, pack sizes, and product instructions before ordering materials.