ClarityHow to use this tool
- Enter area to cover, coverage per roll, waste allowance.
- Select Calculate to view the result.
- Check the method and assumptions below before using the result.
Input reference and sample values
Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.
| Input | Format and units | Sample |
|---|---|---|
| Area to cover | Numeric value. Unit: m². Must be greater than zero. | 20 |
| Coverage per roll | Numeric value. Unit: m². Must be greater than zero. | 25 |
| Waste allowance | Numeric value. Unit: %. Zero or positive. Maximum: 100. | 10 |
Result for these sample inputs
1 rolls
Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.
The method, explained
Rolls = ceil[area × (1 + overlap/waste allowance/100)/roll area].
Using area to cover = 20 m², coverage per roll = 25 m², waste allowance = 10 %, the result is 1 rolls. Change these example inputs to match your task; use the method above to check each step.
What to keep in mind
A material-quantity estimate, not a structural design or building-code check. Confirm site measurements, supplier coverage and waste before ordering.
Methodology maintained by ClarityKit. How these tools are built and checked.