justyourcalculatorRoofing Calculator
Roof area, squares and shingle bundles from your house footprint and pitch.
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Roofing Calculator
Roof area, squares and shingle bundles
10% for gable, 15% for hip roofs.
Roof area
1,860 sq ft
18.6 squares before waste
- Roofing squares with waste1 square = 100 sq ft
- 20.46
- Shingle bundles3 bundles per square (architectural shingles)
- 62
- Underlayment rolls15 lb felt, about 400 sq ft per roll
- 6
- Pitch26.6°, slope factor 1.118
- 6/12
Works for simple gable and hip roofs, where every plane has the same pitch. Measure dormers and different-pitch sections separately. Bundle coverage varies by product.
How it was calculated
- Footprint with overhang: (50 + 2) × (30 + 2) = 1,664 sq ft
- Slope factor = √(1 + (6 ÷ 12)²) = 1.118
- Roof area = 1,664 × 1.118 = 1,860.4 sq ft
- With 10% waste: 2,046.4 sq ft = 20.46 squares
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How the roofing calculator works
Roof area = the footprint of the house plus the overhangs, multiplied by a slope factor. For a pitch of x inches rise per 12 inches run, the factor is √(1 + (x ÷ 12)²). A 6/12 roof is about 1.118 times its footprint; 12/12 is 1.414.
Roofing is sold by the square, which is 100 square feet. Most architectural asphalt shingles come 3 bundles to the square. Add 10% for waste on a gable roof and around 15% on a hip roof with more cuts.
Using and checking your result
Published by JustYourCalculator. Check the units and assumptions above, and compare a known example before relying on the output. Calculations use browser arithmetic and may round displayed values.
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