Shingle Calculator – Loan calculator

Shingle Quantity Calculator

Roof Length (feet):

Roof Width (feet):

Roof Pitch Rise (e.g., 6 for 6/12 pitch): Enter the 'rise' value of your roof pitch (e.g., for a 6/12 pitch, enter 6).

Waste Factor (%): Typically 10-15% for simple roofs, more for complex designs.

Shingle Coverage per Bundle (sq ft): Standard 3-tab shingles often cover ~33.3 sq ft/bundle. Check your shingle product specifications.

Enter your roof dimensions and details above to calculate the estimated shingle quantity.

function calculateShingles() { var roofLength = parseFloat(document.getElementById("roofLength").value); var roofWidth = parseFloat(document.getElementById("roofWidth").value); var roofPitchRise = parseFloat(document.getElementById("roofPitchRise").value); var wasteFactor = parseFloat(document.getElementById("wasteFactor").value); var shingleCoveragePerBundle = parseFloat(document.getElementById("shingleCoveragePerBundle").value); var resultDiv = document.getElementById("shingleResult"); // Input validation if (isNaN(roofLength) || roofLength <= 0 || isNaN(roofWidth) || roofWidth <= 0 || isNaN(roofPitchRise) || roofPitchRise < 0 || isNaN(wasteFactor) || wasteFactor < 0 || isNaN(shingleCoveragePerBundle) || shingleCoveragePerBundle <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers for all fields."; return; } // Assume roof pitch run is 12 (standard) var roofPitchRun = 12; // Calculate slope multiplier // Formula: sqrt(1 + (rise/run)^2) var slopeMultiplier = Math.sqrt(1 + Math.pow(roofPitchRise / roofPitchRun, 2)); // Calculate flat roof area var flatRoofArea = roofLength * roofWidth; // Calculate actual roof surface area (accounting for pitch) var totalRoofSurfaceArea = flatRoofArea * slopeMultiplier; // Calculate area with waste factor var areaWithWaste = totalRoofSurfaceArea * (1 + (wasteFactor / 100)); // Calculate number of bundles var numBundles = areaWithWaste / shingleCoveragePerBundle; // Calculate number of roofing squares (1 square = 100 sq ft) var numSquares = areaWithWaste / 100; // Display results resultDiv.innerHTML = "

Estimated Shingle Requirements:

" + "Total Roof Surface Area: " + totalRoofSurfaceArea.toFixed(2) + " sq ft" + "Area with Waste: " + areaWithWaste.toFixed(2) + " sq ft" + "Estimated Shingle Bundles Needed: " + Math.ceil(numBundles) + " bundles (rounded up)" + "Estimated Roofing Squares Needed: " + numSquares.toFixed(2) + " squares" + "Always round up to the nearest whole bundle when purchasing."; }

Understanding Your Shingle Needs with a Shingle Calculator

Estimating the correct number of shingles for a roofing project is crucial for both budgeting and efficient project management. Too few, and you face delays; too many, and you've wasted money. Our Shingle Quantity Calculator helps homeowners and contractors accurately determine the materials needed for a standard gable roof.

How to Use the Shingle Calculator

To get an accurate estimate, you'll need a few key measurements and details about your roof and the shingles you plan to use:

Roof Length (feet): Measure the total length of your roof from one end to the other. For a simple rectangular roof, this is straightforward. For more complex roofs, you might need to break it down into sections.
Roof Width (feet): Measure the width of your roof. Again, for a simple rectangular roof, this is the width of one side.
Roof Pitch Rise (e.g., 6 for 6/12 pitch): Roof pitch describes the steepness of your roof. It's expressed as a ratio, typically "X/12," where 'X' is the number of inches the roof rises vertically for every 12 inches it extends horizontally. For example, a 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. You can often find this by measuring from inside your attic or by using a level and tape measure on the roof's edge.
Waste Factor (%): This accounts for shingles that will be cut, damaged, or simply wasted during installation. A typical waste factor for a simple gable roof is 10-15%. For more complex roofs with many valleys, hips, or dormers, you might need to increase this to 15-20% or even more.
Shingle Coverage per Bundle (sq ft): Shingles are typically sold in bundles. The coverage area per bundle varies by shingle type and manufacturer. Standard 3-tab asphalt shingles often cover around 33.3 square feet per bundle (meaning 3 bundles make up one "square" of roofing). Architectural or laminate shingles might have different coverage rates. Always check the product specifications on the shingle packaging or manufacturer's website.

Understanding Roofing "Squares" and Bundles

In the roofing industry, materials are often measured in "squares." One roofing square is equal to 100 square feet of roof area. This calculator provides estimates in both total square feet (including waste) and the equivalent number of roofing squares, as well as the estimated number of shingle bundles you'll need.

How the Calculation Works

The calculator first determines the flat footprint area of your roof (Length x Width). Then, it uses the roof pitch to calculate the actual surface area of the sloped roof planes. A steeper roof will have a larger surface area than a flatter roof with the same footprint. Finally, it adds the specified waste factor and divides the total required area by the coverage per shingle bundle to give you the estimated number of bundles.

Example Calculation

Let's say you have a roof with the following characteristics:

Roof Length: 40 feet
Roof Width: 25 feet
Roof Pitch Rise: 6 (for a 6/12 pitch)
Waste Factor: 10%
Shingle Coverage per Bundle: 33.3 sq ft

Here's how the calculator processes this:

Flat Area: 40 ft * 25 ft = 1000 sq ft
Slope Multiplier (for 6/12 pitch): √(1 + (6/12)²) = √(1 + 0.25) = √1.25 ≈ 1.118
Total Roof Surface Area: 1000 sq ft * 1.118 = 1118 sq ft
Area with Waste: 1118 sq ft * (1 + 10/100) = 1118 sq ft * 1.10 = 1229.8 sq ft
Number of Bundles: 1229.8 sq ft / 33.3 sq ft/bundle ≈ 36.93 bundles
Rounded Bundles: You would need to purchase 37 bundles.
Number of Squares: 1229.8 sq ft / 100 sq ft/square ≈ 12.30 squares

Important Considerations

Complex Roofs: This calculator is best suited for simple gable roofs. For roofs with multiple hips, valleys, dormers, or other complex features, the actual surface area can be significantly higher, and the waste factor may need to be adjusted upwards.
Starter Shingles & Ridge Caps: This calculator estimates field shingles. Remember to account for starter shingles (often sold separately or made from cut field shingles) and ridge cap shingles, which are also typically sold in separate bundles.
Professional Advice: While this calculator provides a good estimate, it's always recommended to consult with a professional roofing contractor. They can perform a precise measurement, account for all roof complexities, and provide an exact material list.