Hip vs. Gable Roof Area

Explaining why a hip and a gable roof over the same footprint and pitch share the same surface area, yet differ in waste and cap.

It surprises many people, but a hip roof and a gable roof over the same eave footprint and the same pitch have exactly the same sloped surface area. Area is footprint multiplied by the pitch multiplier, and neither of those changes when you hip the ends instead of gabling them.

Same footprint and pitch, same area

On a gable roof the two long faces are rectangles. On a hip roof the long faces become trapezoids and the ends become triangles, but when you add the pieces up they total the same area as the two gable rectangles. The example below uses one equal input to show this.

An equal-input example

Take a 40 × 24 ft footprint at 6/12. The multiplier is about 1.118. Both the gable and the hip version have an area of 40 × 24 × 1.118 ≈ 1,073.3 sq ft. The hip version splits that into two triangles and two trapezoids; the gable version keeps two rectangles. Same total, different shapes.

Where they differ

The hip roof has four hips instead of two gable ends, so it needs more hip-and-ridge cap and typically more cutting waste, because jack rafters and angled courses create more offcuts. The gable roof has rake edges instead. So budget the same field area for both, but expect different cap totals and a different waste allowance. Check both in the hip calculator and the area calculator.