How to Use the 4/12 Pitch Roof Calculator

A 4/12 Pitch Roof Calculator estimates the total surface area of a gable roof with a 4/12 pitch based on the building's width and length.

What It Does:

A 4/12 pitch means the roof rises 4 inches for every 12 inches of horizontal run. This calculator helps homeowners, contractors, and roofers estimate how much roofing material will be needed by calculating the true roof surface area, which is greater than the flat footprint due to the slope.

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Steps to Use:

1. Enter the width of your building in feet (side to side, gable to gable).
2. Enter the length of your building in feet (ridge direction).
3. Click the “Calculate Roof Area” button.

You’ll get an estimate of the total roof surface area in square feet, accounting for both sloped sides of the roof.

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Example:

For a building that is 30 feet wide and 50 feet long:

• A 4/12 pitch translates to a slope factor of approximately 1.054.
• The actual roof area would be 2 × (15 × 1.054) × 50 ≈ 1581 sq ft.

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4/12 Pitch Roof Calculator FAQ

Q1: What does a 4/12 pitch mean?
A: It means the roof rises 4 inches vertically for every 12 inches of horizontal run—equivalent to an 18.43° slope.

Q2: Is the result for both sides of the roof?
A: Yes, the calculator estimates the combined area of both sloped surfaces in a gable roof.

Q3: Does this include overhangs or eaves?
A: No. This basic version calculates area based only on the building's footprint. Add eave widths manually if needed.

Q4: Can I change the pitch?
A: This tool is fixed to a 4/12 pitch. Let me know if you want a version with adjustable pitch options.

Q5: Is this accurate for a hip roof or other styles?
A: No. This calculator is only for gable roofs with a 4/12 pitch. Hip, shed, or other roof types require different formulas.