How many shingles do I need?

Roof pitch is the angle of the roof expressed as rise over run (e.g., 6/12 means the roof rises 6 inches for every 12 inches of horizontal run). Steeper pitches have more surface area and require more material. If you are unsure of your pitch, measure the vertical rise over 12 inches horizontally using a level and tape measure.

• Standard shingles: 3 bundles per square
• Architectural shingles: 3-4 bundles per square (check package)
• Underlayment: 1 roll per 4 squares (approx 400 sq ft)
• Ridge caps: 1 bundle covers about 35 linear feet of ridge
• Drip edge: Measure the roof perimeter in feet

Add 10-15% for waste, especially on roofs with valleys, hips, and complex shapes.

For example, for a 40×20 ft roof with a 6/12 pitch (pitch factor 1.12):

1. Total roof area = 40 × 20 × 1.12 = 896 sq ft
2. Roofing squares = 896 ÷ 100 = 8.96 squares
3. Shingle bundles = 8.96 × 3 = 26.9 → 27 bundles
4. Underlayment rolls = 8.96 ÷ 4 = 2.24 → 3 rolls
5. Add 10% for ridge caps, starter strips, and waste: 30 bundles