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Roofing Materials Calculator

Estimates shingles, underlayment, flashing, and plywood needed for roof replacement or new construction. Adjusts for roof slope.

Results

Roof Area
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sqft (with waste)
Squares
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Bundles
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Underlayment Rolls
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Materials Order List

Material quantities include waste factor. Actual shingle counts may vary by brand and style. Consult manufacturer specs for exact coverage.

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How to Use This Calculator

1. Choose your input method. Enter the known roof area directly, or enter the house footprint dimensions and pitch to calculate the roof area.

2. Select roofing material. Different materials have different coverage rates and ordering units.

3. Set waste factor. Simple gable roofs need 10%. Hip roofs with valleys need 15-20%.

How the Formula Works

Slope_Factor = SQRT(Rise^2 + Run^2) / Run

Roof_Area = Footprint x Slope_Factor

Bundles = Roof_Area / 33 (asphalt)

Squares = Roof_Area / 100

Frequently Asked Questions

How many bundles of shingles do I need?
One bundle covers approximately 33 sqft. Three bundles make one square (100 sqft). Divide your roof area by 33 and round up, then add 10-15% for waste.
How do I calculate roof area from ground measurements?
Multiply the footprint area by the slope factor for your roof pitch. A 6:12 pitch has a factor of 1.118.
What is a roofing square?
A roofing square is 100 square feet, the standard unit for ordering roofing materials.

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