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Calculators / Construction / Roofing area
Roofing area calculator
Estimate sloped roof area from plan area and roof pitch angle.
On this page
Sloped roof area110.34square units
Material with waste121.37square units
Calculator controls
How to calculate
Estimate sloped roof area from plan area and roof pitch angle.
Sloped roof area = plan/cos(angle*pi/180); Material with waste = plan/cos(angle*pi/180)*(1+waste/100)
Worked example
Horizontal plan area: 100; Roof angle (degrees): 25; Waste allowance (%): 10.
Sloped roof area: 110.34 square units; Material with waste: 121.37 square units.
Assumptions and limits
Complex roofs need each plane measured separately, with overlaps and product-specific coverage.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
Estimate sloped roof area from plan area and roof pitch angle. The displayed figures use the inputs and formula shown on this page.
When this tool is useful
Use the roofing area to compare a scenario, check an estimate, or verify a manual calculation.
Understanding your inputs
| Input | What to enter |
|---|---|
| Horizontal plan area | Enter a number of at least 0.000001 and no more than 1000000000000. |
| Roof angle (degrees) | Enter a number of at least 0 and no more than 80. |
| Waste allowance (%) | Enter a number of at least 0 and no more than 100. |
Frequently asked questions
What should I check before using the roofing area result?
Complex roofs need each plane measured separately, with overlaps and product-specific coverage.
Is this roofing area result exact?
It is exact for the stated mathematical model and entered values. Real-world results can differ when rates, timing, fees, definitions or measurement conditions differ.