Roofing Calculator
Calculate roofing materials needed. Enter roof dimensions and pitch to find total area, shingles, and bundles required.
Enter roof dimensions and pitch.
Roofing Calculation
Roof area = Footprint area × Pitch multiplier
Squares = Roof area / 100
Bundles (3-tab) = Squares × 3
Squares = Roof area / 100
Bundles (3-tab) = Squares × 3
One "roofing square" = 100 sq ft. Standard shingle bundles cover 1/3 of a square (33.3 sq ft each).
Example: 40 ft × 25 ft footprint, 4/12 pitch (multiplier 1.054).
Area = 40 × 25 × 1.054 = 1,054 sq ft
Squares = 1,054 / 100 = 10.54 squares
Bundles = 11 × 3 = 33 bundles
Area = 40 × 25 × 1.054 = 1,054 sq ft
Squares = 1,054 / 100 = 10.54 squares
Bundles = 11 × 3 = 33 bundles
FAQ
How much waste should I add?
Add 10–15% for waste, hip/ridge caps, and cutting. Complex roof shapes may need up to 20% extra.
What is a roof pitch multiplier?
It converts the flat footprint area to actual roof surface area accounting for the slope. A steeper roof has more surface area than its footprint.
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Last updated: 2026-08-08