Roof Calculator

Roof Area & Material Estimator

Calculation Results:

Calculated Roof Area (flat projection): — sq ft

Sloped Roof Area: — sq ft

Total Roof Area (incl. waste): — sq ft

Estimated Shingle Squares: — squares

Estimated Shingle Bundles: — bundles

function calculateRoof() { var roofLength = parseFloat(document.getElementById('roofLength').value); var roofWidth = parseFloat(document.getElementById('roofWidth').value); var pitchRise = parseFloat(document.getElementById('pitchRise').value); var pitchRun = parseFloat(document.getElementById('pitchRun').value); var wasteFactor = parseFloat(document.getElementById('wasteFactor').value); if (isNaN(roofLength) || isNaN(roofWidth) || isNaN(pitchRise) || isNaN(pitchRun) || isNaN(wasteFactor) || roofLength <= 0 || roofWidth <= 0 || pitchRise < 0 || pitchRun <= 0 || wasteFactor < 0) { document.getElementById('calculatedAreaDisplay').innerHTML = 'Calculated Roof Area (flat projection): Please enter valid positive numbers for all fields.'; document.getElementById('slopedAreaDisplay').innerHTML = 'Sloped Roof Area: — sq ft'; document.getElementById('totalAreaDisplay').innerHTML = 'Total Roof Area (incl. waste): — sq ft'; document.getElementById('shingleSquaresDisplay').innerHTML = 'Estimated Shingle Squares: — squares'; document.getElementById('shingleBundlesDisplay').innerHTML = 'Estimated Shingle Bundles: — bundles'; return; } // Calculate the flat projected area var flatProjectedArea = roofLength * roofWidth; // Calculate the pitch angle in radians var pitchAngleRad = Math.atan(pitchRise / pitchRun); // Calculate the pitch multiplier (factor to convert flat area to sloped area) var pitchMultiplier = 1 / Math.cos(pitchAngleRad); // Calculate the actual sloped roof area var slopedRoofArea = flatProjectedArea * pitchMultiplier; // Calculate total area including waste var totalAreaWithWaste = slopedRoofArea * (1 + (wasteFactor / 100)); // Calculate shingle squares (1 square = 100 sq ft) var shingleSquares = totalAreaWithWaste / 100; // Calculate shingle bundles (typically 3 bundles per square) var shingleBundles = shingleSquares * 3; document.getElementById('calculatedAreaDisplay').innerHTML = 'Calculated Roof Area (flat projection): ' + flatProjectedArea.toFixed(2) + ' sq ft'; document.getElementById('slopedAreaDisplay').innerHTML = 'Sloped Roof Area: ' + slopedRoofArea.toFixed(2) + ' sq ft'; document.getElementById('totalAreaDisplay').innerHTML = 'Total Roof Area (incl. waste): ' + totalAreaWithWaste.toFixed(2) + ' sq ft'; document.getElementById('shingleSquaresDisplay').innerHTML = 'Estimated Shingle Squares: ' + shingleSquares.toFixed(2) + ' squares'; document.getElementById('shingleBundlesDisplay').innerHTML = 'Estimated Shingle Bundles: ' + Math.ceil(shingleBundles) + ' bundles'; // Round up for bundles }

Understanding Your Roof Area & Material Needs

Estimating the size of your roof and the materials required is a crucial first step for any roofing project, whether it's a repair, replacement, or new construction. Our Roof Area & Material Estimator helps you quickly determine the approximate square footage of your roof and the number of shingle squares and bundles you'll need.

Why Use a Roof Calculator?

• Accurate Material Ordering: Avoid over-ordering or under-ordering materials, saving time and money.
• Budgeting: Get a clearer picture of material costs for your project.
• Contractor Quotes: Have a baseline understanding of your roof's size when discussing with contractors.
• DIY Planning: Essential for homeowners planning to tackle roofing tasks themselves.

Key Factors in Roof Calculation:

Roof Length and Width

These are the basic dimensions of your roof's footprint. For a simple gable roof, you'd measure the length of the ridge and the width from eave to eave. For more complex roofs, you might need to break it down into simpler rectangular sections and sum their areas.

Roof Pitch (Rise over Run)

Roof pitch describes the steepness of your roof. It's expressed as a ratio, typically "rise over run," where 'rise' is the vertical measurement (in inches) and 'run' is the horizontal measurement (usually 12 inches). For example, a "6/12 pitch" means the roof rises 6 inches for every 12 inches of horizontal run. The steeper the pitch, the larger the actual surface area of the roof compared to its flat footprint.

Our calculator uses the rise and run to determine the pitch multiplier, which accounts for the increased surface area on a sloped roof.

Waste Factor

When installing roofing materials, there's always some waste due to cuts, trimming, and potential errors. A waste factor is added to the calculated area to ensure you have enough materials. Common waste factors range from 10% to 15%, but can be higher for complex roofs with many valleys, hips, and dormers.

Shingle Squares and Bundles

Roofing materials, especially asphalt shingles, are often sold in "squares." One roofing square covers 100 square feet of roof area. Shingles are typically packaged in bundles, with 3 bundles usually making up one square. Our calculator provides estimates for both squares and bundles, rounding up the bundles to ensure you have enough for the job.

How to Use the Calculator:

1. Enter Roof Length (feet): Measure the total length of your roof.
2. Enter Roof Width (feet): Measure the total width of your roof.
3. Enter Roof Pitch Rise (inches): Determine your roof's rise (e.g., 6 for a 6/12 pitch).
4. Enter Roof Pitch Run (inches): This is typically 12 inches.
5. Enter Waste Factor (%): Input your estimated waste percentage (e.g., 10 for 10%).
6. Click "Calculate Roof Materials": The results will display the flat projected area, the actual sloped area, the total area including waste, and the estimated shingle squares and bundles needed.

Example Calculation:

Let's say you have a simple gable roof that is 40 feet long and 25 feet wide, with a 6/12 pitch, and you want to account for a 10% waste factor.

• Roof Length: 40 feet
• Roof Width: 25 feet
• Roof Pitch Rise: 6 inches
• Roof Pitch Run: 12 inches
• Waste Factor: 10%

Based on these inputs, the calculator would provide:

• Calculated Roof Area (flat projection): 1000.00 sq ft (40 * 25)
• Sloped Roof Area: Approximately 1118.03 sq ft (accounting for the 6/12 pitch)
• Total Roof Area (incl. waste): Approximately 1230.00 sq ft (1118.03 * 1.10)
• Estimated Shingle Squares: Approximately 12.30 squares
• Estimated Shingle Bundles: 37 bundles (12.30 * 3, rounded up)

This tool provides a solid estimate for planning your roofing project. Always consult with a professional roofer for precise measurements and material recommendations.