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Volume with a waste allowance
Adds the extra mix consumed by an uneven sub-base, bulging formwork and spillage. Ten percent is a typical allowance for hand pours.
The Formula
V_total = V x (1 + w)
Adds the extra mix consumed by an uneven sub-base, bulging formwork and spillage. Ten percent is a typical allowance for hand pours.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| V | Geometric volume | cubic metres | The volume the finished slab occupies. |
| w | Waste allowance | dimensionless | A decimal: 0.1 for ten percent, 0.05 for five percent. |
| V_total | Order volume | cubic metres | What to buy or order, always larger than V. |
What Each Symbol Means
Vcubic metres
Geometric volume
The volume the finished slab occupies.
wdimensionless
Waste allowance
A decimal: 0.1 for ten percent, 0.05 for five percent.
V_totalcubic metres
Order volume
What to buy or order, always larger than V.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate concrete volume page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Concrete Volume, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.