Roofing Shingles Calculator
Calculate the exact number of roofing shingles needed for any roof size and pitch. Includes waste allowance for hips, valleys, and cuts.
Roofing Quantities Explained
The Roofing Square
One roofing square = 100 square feet (9.29 m²). Standard three-tab shingles come 3 bundles per square. Architectural / dimensional shingles may require 4 bundles per square — check your product specifications.
Pitch Multiplier
A steeper roof has more actual surface area than its footprint suggests. A 4:12 pitch (standard UK house) adds 6% to the footprint area. A 12:12 pitch (45° angle) adds 41% — this is where estimates go badly wrong if ignored.
Waste Allowance by Complexity
Simple gable roof: 10%. Hip roof with 4 sides: 12–15%. Roof with dormers, skylights, or multiple valleys: 15–20%. Always order from the same batch and keep 1–2 spare bundles for future repairs.
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