Roof Sheet Calculator
Calculate how many roofing sheets you need from roof area, sheet width and overlap for Colorbond or metal roofing, free in your browser.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the width to cover (m) and the sheet's effective (laid) cover width (mm).
- Read the sheets per row.
How it works
Sheets per row = width ÷ effective cover width, rounded up.
Worked example
12 m wide, 760 mm cover. = 16 sheets per row.
Common mistakes
- Using the total sheet width instead of the laid cover width (sheets overlap).
- Forgetting end laps and extra rows for long roofs.
Frequently asked questions
How many roof sheets do I need?
Roof width ÷ the sheet's effective cover width gives the number of sheets per row; the tool also allows for overlap and length.
Why use effective cover width?
Corrugated and trapezoidal sheets overlap at the sides, so each covers less than its full width — sizing on cover width avoids coming up short.
What's effective cover width?
The width a sheet covers once lapped with the next — always less than the full sheet width. Check the profile's spec.
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Cite this tool
Zerdly. (2026). Roof Sheet Calculator. Retrieved from https://www.zerdly.com/tools/roof-sheet-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.