Roofing Calculator
The Roofing Calculator converts your building's footprint and roof pitch into actual roof surface area and roofing squares, the standard unit for ordering shingles.
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How This Tool Works
Enter your building's footprint dimensions and roof pitch (rise over 12) to calculate the true roof surface area and number of roofing squares.
Formula & Method
Roof surface area = footprint × pitch multiplier, where the multiplier is √(1 + (pitch/12)²). Roofing squares = (roof area × (1 + waste%)) ÷ 100.
Example Calculation
A 30×40 ft footprint (1,200 sq ft) with a 6/12 pitch has a roof surface area of about 1,342 sq ft — around 14.8 roofing squares with 10% waste.
Frequently Asked Questions
What is a roofing square?+
A roofing square equals 100 sq ft of actual roof surface — it's the standard unit shingles and other roofing materials are priced and ordered by.
How does pitch affect material needs?+
Steeper roofs have more actual surface area than their footprint suggests. A 12/12 pitch roof has about 41% more surface area than the flat footprint.
Should I hire a professional for roof pitch measurement?+
For accurate ordering on an actual project, have a roofer verify the pitch and measurements — this calculator provides a planning estimate only.
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