Calculators/ Roofing/Hip Roof Calculator
Hip Roof Calculator
Area, hip rafter lengths and materials for a hip roof.
Hip Roof Calculator
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A hip roof has the same surface area as a gable roof over the same footprint and pitch, so the square count is identical. What changes is the waste: every course meets a hip at an angle and needs cutting, so 15% is the realistic allowance rather than 10%.
How this is calculated
- Total area = footprint × the pitch multiplier, same as a gable. The hips redistribute the surface, they do not reduce it.
- The hip rafter runs diagonally, so its horizontal run is the common run × √2. Its length is √(diagonal run² + rise²).
- Ridge length = building length minus building width. A square building gives zero: that is a pyramid hip with four hips meeting at a point.
Frequently asked questions
Does a hip roof use more material than a gable?
The same roofing area, but more waste from angled cuts and more framing lumber for the hip and jack rafters. Budget 15% waste instead of 10.
Why is the hip rafter longer than the common rafter?
Because it travels diagonally across the corner. Its horizontal run is 1.414 times the common run, so it is always noticeably longer for the same rise.