What Is a Roof Gable End Area Calculator?
A gable end wall is shaped like a rectangle with a triangle sitting on top of it — the rectangle runs from the floor or foundation up to the eave line, and the triangle rises from the eave up to the ridge, following the roof's pitch. This calculator adds those two shapes together to give you the total gable end area, which is exactly what you need for siding, sheathing, house-wrap or paint estimates.
It uses the same geometry framers and estimators use by hand: split the wall into a rectangle and a triangle, calculate each separately, then add them.
How to Read Your Results
Total Gable End Area
The full area of one gable end wall, combining the rectangular section and the triangular peak — this is the number to use for material takeoffs.
Rectangular Wall Area
The area of the wall below the eave line — simply width times height, just like a standard rectangular wall.
Triangular Peak Area
The area of the triangle above the eave line, up to the ridge, based on your roof's pitch.
Ridge Height (Rise)
How far the ridge sits above the eave line — this is half the wall width scaled by the pitch ratio, and it's the triangle's height.
Real-World Example
A gable end that's 30 ft wide, with an 8 ft wall height to the eave, on a 6/12 pitch roof:
| Step | Calculation | Result |
|---|---|---|
| Ridge rise | (30 ÷ 2) × (6 ÷ 12) | 7.5 ft |
| Rectangular area | 30 × 8 | 240 sq ft |
| Triangular area | 0.5 × 30 × 7.5 | 112.5 sq ft |
| Total gable end area | 240 + 112.5 | 352.5 sq ft |
That's the area for one gable end — a standard gable roof has two matching ends, so double this figure (705 sq ft) for the full building.
Tips for Estimating Gable Ends
- Double the result for a typical gable roof with two identical ends.
- Subtract window and door openings before ordering siding or sheathing material.
- Steeper pitches mean more triangle area even at the same wall width — don't assume all gable ends on a job are equal just because the footprint is.
- Add 5–10% waste for siding cut at angles along the rake edges.
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Last updated: August 2026 · Reviewed by: Simple Calculator Tools Editorial Team