Calculate how many roofing squares, shingle bundles, and nails you need for your roof project. Enter your roof's footprint dimensions and pitch to get an accurate material estimate including a 10% waste allowance.
| Pitch | Rise per 12" Run | Pitch Factor |
|---|---|---|
| Low slope | 2" | 1.014 |
| Standard | 4–6" | 1.054–1.118 |
| Steep | 8–10" | 1.202–1.302 |
| Very steep | 12" | 1.414 |
Roofing is measured in "squares" — one roofing square equals 100 square feet of roof surface. The number of squares you need depends on the total roof area, which is the footprint of the house multiplied by a pitch factor (steeper roofs have more surface area than flat projections suggest).
A flat roof has a pitch factor of 1.0. As pitch increases, so does the surface area:
One bundle of standard 3-tab shingles covers approximately 33.3 square feet (⅓ of a square). You need 3 bundles per roofing square. Architectural/dimensional shingles may require 4+ bundles per square depending on the product — always check the package coverage before ordering.
Add 10–15% waste for a simple gable roof. For hip roofs, dormers, valleys, and skylights, add 15–20%. Cut pieces can rarely be reused, so generous waste factors save you a second trip to the supply house. Order delivery — bulk shingles are extremely heavy.