Hip roof: what it is, its parts, and how to measure one
A hip roof slopes down on all four sides, with hips running from the corners up to a short ridge, and no gable walls. At one pitch all around, its area is the footprint times the slope factor, its ridge is the length less the width, and each hip is half the width times the hip factor (1.5 at 6:12). A 40 by 30 foot house with 1 foot overhangs at 6:12 has about 1,503 square feet of roof and four 24 foot hips.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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What a hip roof is
A hip roof has four slopes. The two long sides meet at a ridge; the two ends slope up to the ends of the ridge, and the outside corners where the slopes meet are the hips. There are no gable walls, so the eaves run all the way around the house. On a square house the four slopes meet at a point and there’s no ridge at all.
The hip rafters under those corners have to be at least 2 inches nominal thick and as deep as the cut ends of the rafters that frame into them (IRC R802.4.3). The roof rafters guide covers the framing.
Hip or gable
A hip roof and a gable roof over the same footprint at the same pitch have the same roof area. A hip roof trades the gable roof’s rakes and gable walls for hips to cut and cap and eaves on all four sides. The gable roof guide has the side-by-side.
How to measure a hip roof
With the same pitch on all four sides:
- Measure the footprint, overhangs included: length and width.
- Area = length × width × the slope factor (1.054 for 4:12, 1.118 for 6:12, 1.202 for 8:12).
- Ridge = length − width.
- Each hip = half the width × the hip factor, the length of a hip for each foot of run (1.453 for 4:12, 1.500 for 6:12, 1.563 for 8:12).
- Eaves = the whole perimeter.
The hip factor is √(pitch² + 2 × 12²) ÷ 12: the hip runs diagonally across the corner, so it climbs the same height over a longer run than a common rafter.
A worked example
A 40 by 30 foot house with 1 foot overhangs all around, at 6:12:
| Step | Working | Result |
|---|---|---|
| Footprint with overhangs | (40 + 2) × (30 + 2) | 42 by 32 ft |
| Area | 42 × 32 × 1.118 | 1,503 sq ft, 15.0 squares before waste |
| Ridge | 42 − 32 | 10 ft |
| Each hip | (32 ÷ 2) × 1.5 | 24 ft, four of them: 96 ft |
| Eaves | 2 × (42 + 32) | 148 ft |
The same house as a gable roof has 42 feet of ridge, 84 feet of eave and 72 feet of rake. Ridge cap covers the hips and the ridge together: 106 feet on the hip roof. The roofing calculator works out both shapes.
Common questions
What is a hip roof?
A roof that slopes down on all four sides to the eaves, with hips at the corners and no gable walls.
Are hip roofs more expensive than gable roofs?
The roof area is the same on the same house at the same pitch. A hip roof adds hip cuts, hip cap and eaves on all four sides; a gable roof adds rakes and gable walls. A roof estimate prices each by the foot.
What is a Dutch hip roof?
A hip roof with a small gable at the top of each end, above the hips. The roof types guide shows it with the other shapes.
How do I find the length of a hip rafter?
Multiply its run, half the roof’s width with the overhangs included, by the hip factor for the pitch: 1.5 for a 6:12 roof.