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Calculate roof area from footprint, pitch and overhang — includes waste for shingles or metal.
Calculate roof area from footprint, pitch and overhang — includes waste for shingles or metal.
Enter values above and click Calculate — results will appear here with the formula explained.
Roof area is rafter length times building length, times two sides, times waste factor. Rafter length comes from pitch and half-width.
Waste 10% for simple gable, 15% for hip/valley, 5% for standing seam metal.
To use the Roof Area Calculator, enter building length (feet), building width (feet), rise (inches) above for an instant result with full breakdown and formula (Rafter length = sqrt(rise²+run²) × (width/2 / run); Area one side = rafter × length; To...). Adjust values live to compare scenarios, then check the worked example and FAQs below for practical tips and costly mistakes to avoid.
Calculate roof area from footprint, pitch and overhang — includes waste for shingles or metal. Formula: Rafter length = sqrt(rise²+run²) × (width/2 / run).
Roof area is rafter length times building length, times two sides, times waste factor. Rafter length comes from pitch and half-width.
Waste 10% for simple gable, 15% for hip/valley, 5% for standing seam metal.
To use the Roof Area Calculator, enter building length (feet), building width (feet), rise (inches) above for an instant result with full breakdown and formula (Rafter length = sqrt(rise²+run²) × (width/2 / run); Area one side = rafter × length; To...). Adjust values live to compare scenarios, then check the worked example and FAQs below for practical tips and costly mistakes to avoid.
40 ft long, 24 ft wide, 6:12 pitch: rafter ≈13.42 ft, one side 537 sq ft, total 1,074 sq ft, with 10% waste 1,181 sq ft (11.81 squares).
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
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