Roofing Calculator
Estimate roofing squares, bundles and underlayment.
ft
ft
/12
Squares
13.42
1,342 ft²
Shingle bundles
41
3 bundles / square
Underlayment rolls
4
400 ft² rolls
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How the roofing calculator works
Roof area = house footprint × pitch factor. The pitch factor is √(1 + (rise/12)²): a 6:12 roof has a 1.118 factor. A "square" is 100 ft² of roof. Shingles are sold in 3 bundles per square.
Frequently asked questions
How many bundles of shingles do I need?
3 bundles per roofing square. For a 40×30 ft home with a 6:12 roof: about 13.4 squares × 3 = 41 bundles.
What is a roofing square?
100 ft² of roof surface. Shingles are priced per square and packaged in bundles that cover ~33 ft² each.
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