🏠 Roofing Calculator
Calculate roof area, roofing squares (100 sq ft), shingle bundles, underlayment rolls, ridge cap bundles, and total cost for gable, hip, or flat roofs.
Roof Pitch Multipliers
| Pitch | Multiplier | Category |
|---|---|---|
| 2/12 | 1.014 | Low slope |
| 4/12 | 1.054 | Standard |
| 6/12 | 1.118 | Moderate |
| 8/12 | 1.202 | Steep |
| 12/12 | 1.414 | Very steep (45°) |
Frequently Asked Questions
A roofing square equals 100 square feet of roof area. It is the standard unit used by roofing contractors and material suppliers in North America. Three bundles of standard 3-tab asphalt shingles cover one square. Architectural (dimensional) shingles also come 3 bundles per square but each bundle covers slightly less.
Pitch multipliers convert footprint area to actual sloped roof area. A flat roof (0/12) has a multiplier of 1.0. A 4/12 pitch adds about 5.4% more area. A steep 12/12 pitch (45° slope) adds 41.4% more area. Higher pitch = more material needed.
Standard 3-tab and most architectural asphalt shingles: 3 bundles per square. Heavy architectural/laminated shingles: sometimes 4 bundles per square — check the manufacturer label. Each bundle weighs 50–80 lbs. This calculator uses 3 bundles per square as the standard.
A gable roof has two triangular ends (gables) and two sloped planes. The sloped area = footprint × pitch multiplier. A hip roof has four sloped planes and no vertical gable ends — it has slightly more surface area than a gable of the same footprint. This calculator applies an additional 5% area factor for hip roofs to account for the extra hip sections.
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