Estimate the roof area, number of roofing squares, and bundles of shingles needed for your roof.
The Roofing Shingle Calculator estimates how much roofing material you need, converting your roof’s flat footprint into actual sloped area, roofing squares, and bundles of shingles.
Roofers measure area in "squares" (100 sq ft each) and shingles are typically sold in bundles of about 33 sq ft, with roughly 3 bundles per square.
Roof Area = Footprint Area × Pitch Multiplier × (1 + Waste %). Squares = Roof Area ÷ 100. Bundles = Squares × 3.
A 40 ft × 30 ft footprint (1,200 sq ft) with a 6/12 pitch and 10% waste needs about 1,472 sq ft of roofing, or roughly 15 squares and 45 bundles of shingles.
Total roof surface area (accounting for pitch), converted to "squares" (100 sq ft units).
A steeper pitch increases actual surface area compared to the home's footprint.
Yes, typically 10-15% extra for cuts and roof features.