Hip roof calculator

This calculator will help you estimate hip roof parameters, including rafters and roof area

This page exists due to the efforts of the following people:

One of users asked us to create calculator which will help him estimate hip roof parameters, like rafter's lengths, roof rise and roof area.

Here it is. To get results you need to provide roof base dimensions (length and width) and roof pitch (we assume it is identical for all sides). All formulae are below the calculator.


Hip roof calculator

Roof base length (a)

Roof base width (b)

Roof pitch or roof slope (degrees)

Digits after the decimal point: 5
Common rafter length
Hip rafter length
Roof rise (h)
Roof area
Ridge board length (C)

Pyramid hip roof

Hip roof

Here we consider two types of hipped roofs (see picture):
1) Pyramid hip roof - roof base is a square, roof sides are identical isosceles triangles
2) Hip roof - roof base is a rectangle, two sides are identical isosceles triangles and two sides are identical trapeziums.

  • Roof rise: h=\frac{b \tan \alpha}{2}
  • Common rafters: e=\frac{b}{2 \cos \alpha}
  • Hip rafters: d=\sqrt{h^2+\left(\sqrt{(\frac{b}{2})^2+(\frac{b}{2})^2}\right)^2}=\sqrt{h^2 +\frac{b^2}{2}} - pythagoras theorem
  • Roof area: S=4\frac{eb}{2}+2(a-b)e=2e(b+a-b)=2ea