Formula
Roof area = footprint area x pitch factor. Pitch factor = sqrt(12² + rise²) / 12. Roofing squares = roof area / 100. Bundles = ceiling(area with waste / bundle coverage).
Roof material estimator
Roofing Calculator
Estimate roof surface area, roofing squares, shingle bundles, and material cost using building footprint, roof pitch, waste allowance, and bundle coverage.
Calculate roofing materials
Roof area
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Roofing squares
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Bundles needed
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Estimated material cost
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Example
A 40 ft by 28 ft footprint with 6/12 pitch has about 1,252 sq ft of roof area before waste. With 10% waste and 33.3 sq ft per bundle, estimate about 42 bundles.
Useful for
Asphalt shingle estimates, roof replacement planning, roofing square checks, material budgeting, and contractor quote comparison.
Roofing estimate notes
This calculator uses a simplified footprint method. Complex roofs with dormers, hips, valleys, multiple slopes, waste from starter strips, and ridge caps may require more material.
FAQ
What is a roofing square?
One roofing square equals 100 square feet of roof surface area.
Does this include ridge caps and underlayment?
No. It estimates main roof covering only. Add ridge caps, starter shingles, underlayment, flashing, nails, vents, and disposal separately.