Roofing Calculator
Calculate roof area and shingle squares needed by pitch.
About this tool
The flat footprint of a house is smaller than its actual roof surface, because a sloped roof has more area than the ground it covers. This calculator applies the standard pitch multiplier to your footprint area, then converts to roofing 'squares' (100 sq ft each) with a waste allowance for cuts and overlaps.
Key Features
- Pitch-adjusted actual roof area
- Converts to roofing squares (100 sq ft units)
- Adjustable waste allowance
How to Use
- Enter the roof's footprint area (the building's floor area, roughly).
- Enter the roof pitch as rise per 12 inches of run — a common '6/12' roof is entered as 6.
- Enter a waste allowance.
- Click Calculate Roofing.
Benefits
- Order the right number of shingle squares
- Understand why a steep roof needs more material than its footprint suggests
- Estimate material cost before calling a contractor
Frequently Asked Questions
One square equals 100 square feet of roof surface — shingles and other roofing materials are typically sold and estimated by the square, not by the square foot.
A steeper roof has more actual surface area than its flat footprint — a 6/12 pitch roof (rising 6 inches for every 12 inches of horizontal run) has about 12% more surface area than the footprint alone, and steeper pitches add even more.