Hip Roof Area & Rafter Calculator
Calculate surface area, ridge length, and rafter dimensions for hip roofs (4 sloping sides). Optimized for estimating sheathing and shingles.
About
A hip roof has four sloping sides that meet at a ridge, requiring more complex calculations than a standard gable roof. This calculator breaks down the geometry into triangular and trapezoidal sections to determine the exact sheathing area. It also calculates the Common Rafter length (for the main slopes) and the Hip Rafter length (the diagonal beam where slopes meet). Accurate Hip Rafter calculation is critical for structural framing, as these beams are significantly longer than common rafters. The logic assumes equal pitch on all four sides.
Formulas
Key framing lengths are derived from the span and pitch:
Common Rafter = Run × √1 + (pitch/12)2
Hip Rafter = Run × √2 + (pitch/12)2
Ridge Length = Length − Width
Reference Data
| Pitch | Common Multiplier | Hip Multiplier | Example (Span 24') |
|---|---|---|---|
| 4/12 | 1.054 | 1.453 | Hip Len: 17.4 ft |
| 6/12 | 1.118 | 1.500 | Hip Len: 18.0 ft |
| 8/12 | 1.202 | 1.563 | Hip Len: 18.8 ft |
| 10/12 | 1.302 | 1.641 | Hip Len: 19.7 ft |
| 12/12 | 1.414 | 1.732 | Hip Len: 20.8 ft |