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Roof Area Calculator
Find the real surface of a pitched roof for materials.
The horizontal area (length × width) is multiplied by a pitch factor of 1/cos(angle). At 30°, the factor is about 1.155.
How it works
The horizontal area (length × width) is multiplied by a pitch factor of 1/cos(angle). At 30°, the factor is about 1.155.
Worked example
A roof 10 m × 8 m at 30°: 80 m² × 1.155 ≈ 92.4 m² of actual roofing surface.
Recommendations
- Add 5–10% for waste, ridges and overlaps
- Higher pitch increases the surface and material cost
- Insulation needs match the sloped surface area
Tips & advice
- Measure the horizontal span, not the slope distance
- Include eaves and overhangs in the total
- For very steep roofs, count each slope separately
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Roof Area Calculator
Find the real surface of a pitched roof for materials.
Use the calculatorInvoice Generator FAQs
Yes, all 20 home calculators are 100% free, private and run entirely in your browser. No account needed.
They use standard industry formulas. Always round up for materials and confirm with a professional for structural work.
The calculators use metric units (meters, liters, m³). Convert imperial measurements beforehand if needed.
No. Calculations happen instantly in your browser and nothing is sent to any server.
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