Hip Roof Calculator
Calculate hip roof area, hip rafter lengths, and material quantities from building dimensions and pitch. Includes all four slopes and hip/valley lengths. Free, no signup.
Roof Area Calculator
Calculate actual roof surface area from plan dimensions and pitch
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Hip roofs — did you know?
How hip roof area differs from gable
A hip roof has 4 slopes instead of 2. The plan area × pitch factor gives total surface area, but hip ends are triangular. For a square building at 35°: total area = plan × 1.221. For rectangles, calculate each slope separately.
Hip rafter count
A rectangular hip roof has 4 hip rafters (one per corner). Each runs from corner to ridge. Common rafters run between hips. At 400mm centres, common rafter count = (ridge_length + 2 × run) ÷ 0.4 + 1.
Why hip roofs waste more material
Hip roofs have compound cuts at every hip junction, triangular hip-end slopes, and shorter common rafters near the hips. Waste is typically 15-20% vs 10% for gable roofs.
Hip roof structural considerations
Hip roofs are more wind-resistant than gable roofs (no large flat gable ends to catch wind). They distribute load to all four walls. But they require more structural elements: hip rafters, jack rafters, and ridge bracing.
Formulas used
Total hip roof area
area = plan_area × (1 ÷ cos(pitch°)) × 1.04
Hip rafter length
hip = hip_run × sqrt((1/cos(pitch°))² + 1)
Common rafter
rafter = run ÷ cos(pitch°)
Jack rafter (shortest)
jack = (hip_spacing ÷ cos(pitch°))
Frequently asked questions
How do I calculate hip roof area?
Plan area × pitch factor × ~1.04 (hip end factor). At 35°, 100 m² plan: 100 × 1.221 × 1.04 = 127 m². For precision, calculate each of the 4 slopes separately.
How many hip rafters does a hip roof have?
4 hip rafters (one per corner) for a rectangular building. Plus common rafters between hips at regular centres.
Why does a hip roof cost more than a gable?
More rafters, compound cuts, 15-20% waste vs 10%, shorter jack rafters near hips. Typically 20-30% more expensive.
Best free hip roof calculator?
One that handles all 4 slopes, hip lengths, jack rafters, and waste. This tool does all, free.