Roofing Calculator
Calculate roof area, roofing squares and shingle bundles with this free online roofing calculator. Includes roof pitch, overhang, waste and underlayment.
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How to use Roofing Calculator
- 1Choose feet or metres and enter the house length, width and eave overhang
- 2Select the roof pitch and a waste allowance
- 3Read the roof area, roofing squares, shingle bundles and underlayment rolls
Frequently asked questions
How many bundles of shingles do I need?▾
Most architectural shingles come 3 bundles per square, and a square covers 100 sq ft. A 40×30 ft house with 1 ft overhangs and a 6/12 pitch has about 1,503 sq ft of roof, or 50 bundles with 10% waste.
How does roof pitch affect roof area?▾
A steeper roof has more surface than its flat footprint. Multiply the footprint by the pitch factor: about 1.054 for 4/12, 1.118 for 6/12, 1.202 for 8/12 and 1.414 for 12/12.
How much waste should I add for roofing?▾
Add about 10% for a simple gable roof and 15% or more for hip roofs or roofs with valleys and dormers, plus extra for starter strips and ridge caps.
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