Roof Sheet Calculator
Find how many corrugated sheets are needed to cover a roof from its area, the sheet size and a wastage allowance.
Enter your numbers
Example: 20
Example: 15
Example: 8
Example: 2.25
Example: 5
Recent
Formula
How the calculation works
The calculator multiplies the roof length by the roof width to get the total roof area in square feet.
It then divides that area by the effective coverage of one sheet, which is the sheet length times its usable width.
The count is rounded up to a whole sheet and a wastage allowance is added for overlaps and cutting.
Common mistakes
- Using the full sheet width instead of the effective width, since corrugation overlaps reduce the area one sheet really covers.
- Measuring the flat ground area rather than the sloped roof area, which underestimates the sheets needed on a pitched roof.
When to use it
- Contractors and homeowners use it to order tin sheets for a shed, garage or house roof.
- It also helps check a quoted sheet count from a supplier before paying.
Worked example
For a roof 20 feet by 15 feet, sheets 8 feet long with an effective width of 2.25 feet cover 18 square feet each, so you need 17 sheets and 18 sheets with 5 percent wastage.
Common questions
What is the effective width of a corrugated sheet?
A standard corrugated sheet is about 8 feet long and, after side overlap, covers roughly 2.25 feet of width, so one sheet covers about 18 square feet.
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