How Many Bundles of Shingles Do I Need for My Roof?

Understanding Roofing Measurements: The "Square"

In the US roofing industry, materials and labor are calculated using a unit called a **Square**. One roofing square is equal to **100 square feet** of roof surface area. A standard bundle of asphalt shingles covers **33.3 square feet**. Therefore, you need exactly **3 bundles to cover 1 square** of roof area.

Step-by-Step Shingle Estimation

1. Find the Footprint Area: Measure the length and width of the home's footprint (including eaves and overhangs). For example, 40 ft × 30 ft = 1,200 sq ft.
2. Apply the Pitch Multiplier: A sloped roof has more surface area than a flat ceiling. Multiply the footprint area by the pitch factor. For a 6:12 pitch (1.118 multiplier):
   1,200 × 1.118 = 1,341.6 sq ft.
3. Convert to Squares: Divide by 100.
   1,341.6 / 100 = 13.42 Squares.
4. Determine Bundles: Multiply squares by 3.
   13.42 × 3 = 40.26 bundles.
5. Add Waste Factor: Add 10% for hip/gabled roof cuts: 40.26 × 1.10 = 44.28 bundles (order 45 bundles).