How to use this calculator
Estimate cubic yards for a rectangular slab. Enter length (feet), width (feet), thickness (inches), extra material (%). The result updates when you change an input. To compare two sets of inputs, save scenario A, then enter the second set; the result panel shows the difference.
Formula and limits
Cubic yards = length(ft) × width(ft) × thickness(in) ÷ 12 ÷ 27, then multiplied by the allowance factor. Check dimensions and supplier requirements before ordering.
Worked example
The following example uses the calculator’s starting values. It is an illustration of the method, not a recommended target.
| Input | Example value |
|---|---|
| Length (feet) | 10 |
| Width (feet) | 10 |
| Thickness (inches) | 4 |
| Extra material (%) | 10 |
Cubic yards including allowance: 1.358
Interpreting your result
Confirm actual dimensions, supplier specifications, and site conditions. Quantity estimates do not establish structural adequacy or compliance with building codes. Waste allowances are user assumptions.
Comparing alternatives
Save the first result as scenario A, then change one input. The comparison shows the numeric difference; it does not label either result as better. Choose inputs that describe realistic alternatives. Values shown on screen are rounded, so calculations from rounded intermediate results may differ slightly.