Hip Roof Area & Shingle Calculator
Calculate framing geometry and material needs for hip roofs. Outputs rafter lengths, squares, and shingle bundles based on pitch.
Total Materials Needed
Framing Geometry
About
A hip roof has slopes on all four sides that come together at the top to form a ridge. Unlike a gable roof, hip roofs are self-bracing and more resistant to wind, but they are significantly harder to estimate due to the complex geometry of the hip rafters and triangular faces. The most common error in estimating hip roofs is underestimating the waste factor; the diagonal cuts required along the hips generate unusable shingle scraps.
This calculator determines the true surface area based on the footprint and the roof pitch (slope). It automatically calculates the lengths of the Common Rafters (running perpendicular to the plate) and the Hip Rafters (running diagonally at the corners). It converts the final area into "Squares" (1 Square = 100 sq ft) and standard shingle bundles, applying a recommended waste factor of 10-15% to buffer against cutting loss.
Formulas
The calculator derives the Roof Surface Area A from the flat footprint Area Aplan and the Pitch Multiplier M.
To calculate the Hip Rafter Length Lhip, we must account for the fact that the hip runs at a 45° angle in the plan view (assuming a square corner). The run of the hip is Run × √2.
Materials are ordered in Squares S and Bundles B.
Reference Data
| Roof Pitch | Slope Angle | Rafter Multiplier | Hip/Valley Multiplier | Est. Waste % |
|---|---|---|---|---|
| 3/12 | 14.0° | 1.031 | 1.436 | 10% |
| 4/12 | 18.4° | 1.054 | 1.453 | 10% |
| 5/12 | 22.6° | 1.083 | 1.474 | 12% |
| 6/12 | 26.6° | 1.118 | 1.500 | 12% |
| 8/12 | 33.7° | 1.202 | 1.563 | 15% |
| 10/12 | 39.8° | 1.302 | 1.642 | 15% |
| 12/12 | 45.0° | 1.414 | 1.732 | 18% |