Roofing Calculator
Calculate roofing squares, shingle bundles, underlayment, and accessories. Enter your building footprint and roof pitch, or a known roof area.
Roof Pitch Multipliers
| Pitch | Multiplier | Angle |
|---|---|---|
| 3/12 | 1.031 | 14° |
| 4/12 | 1.054 | 18.4° |
| 6/12 | 1.118 | 26.6° |
| 8/12 | 1.202 | 33.7° |
| 10/12 | 1.302 | 39.8° |
| 12/12 | 1.414 | 45° |
FAQ
What is a roofing square?
A roofing square is 100 square feet of roof area. It's the standard unit for ordering shingles and estimating roofing jobs. A 2,000 sq ft roof is 20 squares. Most architectural shingle bundles cover about 1/3 of a square, so you need 3 bundles per square.
How does roof pitch affect material quantity?
A steeper pitch means more roof area covering the same building footprint. A 6/12 pitch multiplies the footprint by 1.118x, while a 12/12 (45°) pitch multiplies by 1.414x. That means a 1,500 sq ft footprint with a 12/12 pitch has 2,121 sq ft of actual roof area — 42% more material than a flat roof.
How much waste should I add for roofing?
Add 10% waste for a simple gable roof, 15% for hip roofs, and up to 20% for complex roofs with dormers, valleys, and many penetrations. The extra material accounts for cuts at hips, valleys, rakes, and around vents/chimneys.
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