Gable Roof Area Calculator

Planning a roofing project? A gable roof is one of the most common roof styles, and calculating its area is essential for estimating material costs and project size. Our Gable Roof Area Calculator simplifies this task by allowing you to use either the building footprint and pitch or the actual sloped side measurements.

Methods to Calculate Gable Roof Area

There are two methods to calculate the surface area of a gable roof:

Method 1: Using Building Footprint and Roof Pitch

If you know the length and width of the building and the roof pitch (e.g., 6:12), use this method.

Step 1: Calculate Roof Slope Multiplier

$\text{Slope Multiplier}=\sqrt{1+{\left(\frac{\text{Rise}}{\text{Run}}\right)}^2}$

Step 2: Calculate Total Roof Area

$\text{Roof Area}=2\times (\text{Building Length}\times \text{Building Width}\times \text{Slope Multiplier})$

Method 2: Using Actual Sloped Side Length

If you already know the length of the sloped side (not the footprint), use this simplified method.

Formula:

$\text{Roof Area}=2\times (\text{Building Length}\times \text{Sloped Side Length})$

Example Calculation (Using Method 1)

• Building Length: 40 ft
• Building Width: 20 ft
• Roof Pitch: 6:12

Step 1: Slope Multiplier

$\text{Slope Multiplier}=\sqrt{1+{\left(\frac{6}{12}\right)}^2}=\sqrt{1+0.25}=\sqrt{1.25}\approx 1.118$

Step 2: Roof Area

$\text{Roof Area}=2\times (40\times 20\times 1.118)=2\times 894.4=1788.8\text{sq ft}$

Example Calculation (Using Method 2)

• Building Length: 40 ft
• Sloped Side Length: 23 ft

Roof Area:

$\text{Roof Area}=2\times (40\times 23)=2\times 920=1840\text{sq ft}$

Conclusion

Whether you're a contractor, homeowner, or DIY enthusiast, calculating the gable roof area is the first step in accurate planning. Use the method that fits the data you have, and let our calculator do the hard work for you.

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