Add 10% extra for waste/cuts, and check your specific shingle brand's bundle coverage.
Free Roofing Calculator
A steeper roof pitch means more actual surface area than the footprint below it — this calculator applies a pitch multiplier to convert your building's footprint dimensions into true roof surface area before calculating squares and bundles.
Worked Example
Example: A 30ft × 40ft footprint (1,200 sq ft) with a 6/12 pitch (multiplier ~1.118) → 1,342 sq ft of actual roof area = 13.4 squares ≈ 40 bundles (3 bundles/square is standard).
Formula / Method
Roof Area = Footprint Area × Pitch MultiplierSquares = Roof Area / 100Bundles ≈ Squares × 3 (standard 3-tab shingle coverage)
Worked Example
Example: A 30ft × 40ft footprint (1,200 sq ft) with a 6/12 pitch (multiplier ~1.118) → 1,342 sq ft of actual roof area = 13.4 squares ≈ 40 bundles (3 bundles/square is standard).
Formula / Method
Roof Area = Footprint Area × Pitch MultiplierSquares = Roof Area / 100Bundles ≈ Squares × 3 (standard 3-tab shingle coverage)