ROOFING
ROOFING SHINGLES
sq = footprint × pitch
ft
ft
in
RESULT
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Pitch multiplier: 4/12 = 1.054 · 6/12 = 1.118 · 8/12 = 1.202 · 12/12 = 1.414. 3 bundles per square. 10% waste included.
About this calculator
This roofing calculator estimates the number of shingle bundles you need for a roof. Enter the building footprint length and width and the roof pitch (rise per 12 inches of run), and the calculator computes the actual roof surface area, converts it to roofing squares (1 square = 100 ft²), and returns the bundle count. Most asphalt shingles ship 3 bundles per square. A 10% waste factor for cuts and ridge caps is built in.
Common questions
How long do asphalt shingles last?
3-tab shingles last 15–20 years. Architectural (dimensional) shingles last 25–30 years. Premium shingles can last 40–50 years. Climate matters — southern heat shortens lifespan; northern cold/ice extends it.
How much does a roofing square cost?
Materials only: $90–150 per square for 3-tab shingles, $120–250 for architectural. Installed labor adds $300–500/square. A typical 2,000 ft² roof is 25–30 squares.
How do I figure my roof pitch?
Use a level on the roof or a ladder against the gable. Hold the level horizontal, measure straight down 12 inches from the level, then measure up to the roof — that vertical number is your pitch. A roof rising 6 inches per 12-inch run is "6/12 pitch."