Roof Shingles Calculator (Bundles & Squares)

What this calculates

Roofing is measured in 'squares': 1 square = 100 sq ft. Asphalt shingles come 3 bundles per square. Order 10-15% extra for waste, ridge caps, and starter strips. Roof pitch increases actual surface area beyond the footprint.

Formula & how it works

Roof area = footprint_area × pitch_multiplier. Pitch multipliers: 4/12 → 1.054, 6/12 → 1.118, 8/12 → 1.202, 10/12 → 1.302, 12/12 → 1.414. Squares = area / 100. Bundles = squares × 3 × (1 + waste).

Worked example

Footprint 2,000 sq ft, 6/12 pitch, 12% waste. Roof area = 2,236 sf. Squares 22.4. Bundles = 22.4 × 3 × 1.12 = 75 bundles.

Frequently asked questions