Gable Siding Calculator
Estimate siding for triangular gable ends from measured height or roof pitch, with openings, waste, siding squares, and package rounding.
Enter measurements below. The result updates as you type.
Calculation breakdown
Gable shape
Each gable uses base width x vertical height / 2.
Height source
Measured gable height is used directly.
Net area
144 - 20 = 124 sq ft
Purchase quantity
124 sq ft plus 10% waste, divided by package coverage.
More Siding help
Related calculators and guides
Open the project hub for nearby tools, measurement guidance, and published articles.
Formula explanation
Core gable siding estimate basis
Gable area = base width x vertical gable height / 2; purchase area = net area x (1 + waste)
- Measured-height mode uses the gable height directly.
- Pitch mode estimates vertical height from base width and rise/run.
- One siding square equals 100 square feet.
Example structure
Two matching gables
Two 24 ft wide x 6 ft high gables, 20 sq ft openings, 10% waste
- 1Multiply 24 x 6 / 2 for one gable.
- 2Multiply by two matching gables.
- 3Subtract 20 square feet of openings.
- 4Apply the selected waste allowance and package coverage.
Purchase area: 136.4 square feet, or 1.36 siding squares before package rounding.
Assumptions to verify
Before this calculator goes live
- Each gable is treated as a triangle using base width times vertical height divided by two.
- Pitch mode derives height from half the base width multiplied by rise divided by run.
- Openings are deducted before waste is applied.
- Trim, starter strips, fascia, soffit, and corner accessories are not included.
Measurement checklist
How to measure
- Measure the horizontal base width across the bottom of the gable.
- Measure the vertical height from the base line to the peak, or enter roof pitch rise and run.
- Count matching gables only when they use the same base and height.
- Measure any windows, vents, or doors in the gable as total opening area.
Avoid these errors
Common mistakes
- Using roof slope length instead of vertical gable height.
- Forgetting that a triangular gable is half of a rectangle with the same base and height.
- Deducting openings after waste instead of before waste.
- Ordering gable siding without checking trim, starter, and profile-specific coverage.
Estimate disclaimer
Verify before ordering.
Use the output as a planning baseline. Site conditions, product coverage, waste, supplier units, installation method, and local requirements can change the final quantity.
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Published guides
Understand the measurements and assumptions
Supporting guide
How Much Siding Do I Need?
Add wall and gable areas, subtract openings, convert to siding squares or product coverage units, and apply a clear waste allowance.
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Supporting guide
Vinyl Siding Cost by House Size: Area, Squares, and Scope
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Common questions
Use the result with context
01Does this replace the full siding calculator?+
No. This page is for triangular gable ends only. Use the full siding calculator for whole-house walls, multiple wall sections, and broader siding estimates.
02Can roof pitch be used instead of measuring gable height?+
Yes. Pitch mode derives gable height from half the base width multiplied by rise divided by run, but a measured height is usually better when available.
03Are trim and starter strips included?+
No. The result covers siding area and package rounding only. Confirm trim, starter, corners, vents, and product-specific accessories separately.