Estimated installed cost per roofing "square" (100 sq. ft.), including labor.
No (Overlay)
Yes (Add $60/square)
function calculateRoofingCost() {
// Get input values
var footprintInput = document.getElementById("houseFootprint");
var pitchInput = document.getElementById("roofPitch");
var materialInput = document.getElementById("roofMaterial");
var tearOffInput = document.getElementById("tearOff");
var resultDiv = document.getElementById("calc-result");
var footprint = parseFloat(footprintInput.value);
var pitchMultiplier = parseFloat(pitchInput.value);
var materialCostPerSquare = parseFloat(materialInput.value);
var tearOffCostPerSquare = parseFloat(tearOffInput.value);
// Validation
if (isNaN(footprint) || footprint <= 0) {
resultDiv.style.display = "block";
resultDiv.innerHTML = "Please enter a valid number for the House Footprint.";
return;
}
// Calculation Logic
// 1. Calculate actual roof surface area based on pitch
var roofSurfaceArea = footprint * pitchMultiplier;
// 2. Add Waste Factor (10% standard for cuts and overlap)
var wasteFactor = 1.10;
var totalAreaWithWaste = roofSurfaceArea * wasteFactor;
// 3. Convert to Roofing Squares (1 square = 100 sq ft)
var squares = totalAreaWithWaste / 100;
// Round up to nearest whole square as materials are sold in bundles
var squaresRounded = Math.ceil(squares);
// 4. Calculate Costs
var totalMaterialAndLabor = squaresRounded * materialCostPerSquare;
var totalTearOff = squaresRounded * tearOffCostPerSquare;
var grandTotal = totalMaterialAndLabor + totalTearOff;
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
maximumFractionDigits: 0
});
// Display Result
resultDiv.style.display = "block";
resultDiv.innerHTML = `
Estimated Project Breakdown
Roof Surface Area (w/ Waste):${Math.round(totalAreaWithWaste).toLocaleString()} sq. ft.
Total Squares Required:${squaresRounded} Squares
Material & Installation Cost:${formatter.format(totalMaterialAndLabor)}
${tearOffCostPerSquare > 0 ? `
Old Roof Removal Cost:${formatter.format(totalTearOff)}
` : "}
Total Estimated Cost:${formatter.format(grandTotal)}
*This is a rough estimate. Actual costs vary by region, contractor availability, and roof complexity.
`;
}
How to Estimate Your Roof Replacement Cost
Replacing a roof is one of the most significant investments a homeowner will make. Our Roofing Cost Calculator helps you budget for this project by considering the four main factors that influence the price: footprint size, roof pitch, material choice, and existing roof removal.
What is a "Square"?
In the roofing industry, materials and labor are rarely priced by the square foot. Instead, they are priced by the "Square". One Square equals 100 square feet of roof surface area.
1. Calculating Roof Surface Area
Your roof is always larger than your home's floor plan (footprint). This is due to two factors:
Overhangs: The roof extends past the walls to protect the siding and foundation.
Pitch (Slope): A steeper roof has much more surface area than a flat roof covering the same amount of ground.
Our calculator applies a specific multiplier based on the pitch you select. For example, a steep roof might have 35% more surface area than a flat roof on the same house.
2. Material Options and Pricing
The material you choose has the biggest impact on the final cost. Here is a breakdown of common options included in the estimator:
Asphalt Shingles ($450 – $550 / Square): The most common roofing material in North America. Affordable and durable, typically lasting 20-30 years.
Metal Roofing ($950+ / Square): Standing seam metal roofs are extremely durable, fire-resistant, and can last 50+ years, but come with a higher upfront cost.
Tile & Slate ($1,200+ / Square): These premium materials offer a distinct look and incredible longevity but are very heavy, sometimes requiring structural reinforcement of the roof deck.
3. The "Tear-Off" Factor
If you have an existing roof, it usually needs to be removed before the new one is installed. This process, known as a "tear-off," adds labor and disposal fees to the project. While it is sometimes possible to layer new shingles over old ones (overlay), most professional roofers recommend a full tear-off to inspect the underlying decking for rot or damage.
4. Waste Factor
No roof is a perfect rectangle. Valleys, hips, ridges, and edges require shingles to be cut, resulting in waste material. Professional estimates typically include a 10% to 15% waste factor to ensure there is enough material to complete the job without running short. This calculator automatically applies a 10% waste factor to your surface area calculation.