Gable End Area Calculator
Last reviewed How we calculate
The gable end is the triangular section of wall under the end of a pitched roof. Siding, paint and sheathing for a gable all start from its area, and the triangle is easy to get wrong by eye. This works it out from the wall width and the roof pitch.
Gable wall area for siding or paint
The area of a gable wall, triangle and all, for siding or paint.
How to measure
This calculator needs JavaScript to work. The measurements below are the ones you would need to do the sum by hand.
Wall area to cover
- Gable triangle, each
- Height of the gable
- Siding squares
The triangle is measured to the underside of the roof. Add a waste allowance when ordering siding, more for vertical or patterned products.
How the calculation works
The height of the gable is half the wall width times the pitch over 12. The triangle is half the width times that height. Add any rectangular wall below it, multiply by the number of gable ends, and take off the windows and doors.
A worked example
A gable wall 28 ft wide under a 6 in 12 roof rises 7 ft to the peak, so each triangle is 98 sq ft. A house with two gable ends has 196 sq ft of gable to cover, or just under 2 squares of siding before waste.
Before ordering
Measure to the underside of the roof, not to the top of the shingles. Siding on a gable is cut to an angle at both edges, so allow more waste than for a plain wall, and more again for vertical or patterned siding that has to line up.
Frequently asked questions
How do you work out the area of a gable?
Half the width times the height of the gable. The height is half the width times the pitch over 12, which the calculator works out from the pitch.
Should the wall below the gable be included?
Include it if you are covering it with the same material. Enter its height and the calculator adds the rectangle to the triangle.
How much extra siding should I order for a gable?
More than for a plain wall, because every course is cut to an angle at both ends. 10 per cent is a common starting point, with more for vertical or patterned siding.