Roofing Cost Estimator
Ground floor area, not roof area.
Flat / Low Slope (Up to 3/12)
Moderate Slope (4/12 – 8/12)
Steep Slope (9/12 – 12/12)
Very Steep / Mansard (12/12+)
Asphalt Shingles (Basic) – $4.50/sqft
Architectural Shingles – $6.50/sqft
Metal Seam – $10.00/sqft
Clay/Concrete Tile – $16.00/sqft
Natural Slate – $22.00/sqft
No (Layer Over)
Yes (Tear Off & Disposal) – +$2.00/sqft
Estimated Project Cost
Estimated Roof Area: 0 sq. ft.
*Includes waste factor of 10% for cuts and overlaps.
function calculateRoofCost() {
// Get input values
var baseArea = parseFloat(document.getElementById(‘baseArea’).value);
var pitchMultiplier = parseFloat(document.getElementById(‘roofPitch’).value);
var materialCostPerSqFt = parseFloat(document.getElementById(‘roofMaterial’).value);
var tearOffCostPerSqFt = parseFloat(document.getElementById(‘tearOff’).value);
// Validation
if (isNaN(baseArea) || baseArea <= 0) {
alert("Please enter a valid home footprint area.");
return;
}
// Calculation Logic
// 1. Calculate actual roof surface area based on pitch
var actualRoofArea = baseArea * pitchMultiplier;
// 2. Add waste factor (typically 10-15% for cuts, hips, valleys)
var wasteFactor = 1.10;
var totalBillableArea = actualRoofArea * wasteFactor;
// 3. Calculate Material and Labor cost combined (Input value represents installed cost)
var baseProjectCost = totalBillableArea * materialCostPerSqFt;
// 4. Add Tear Off costs if applicable
var tearOffTotal = totalBillableArea * tearOffCostPerSqFt;
// 5. Total Estimate
var totalEstimate = baseProjectCost + tearOffTotal;
// Create Ranges (+/- 15% for market variance)
var lowEstimate = totalEstimate * 0.85;
var highEstimate = totalEstimate * 1.15;
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
maximumFractionDigits: 0
});
// Update UI
document.getElementById('costLow').innerHTML = formatter.format(lowEstimate);
document.getElementById('costAvg').innerHTML = formatter.format(totalEstimate);
document.getElementById('costHigh').innerHTML = formatter.format(highEstimate);
document.getElementById('totalRoofArea').innerHTML = Math.round(totalBillableArea).toLocaleString();
document.getElementById('resultSection').style.display = 'block';
}
Understanding Your Roofing Estimate
Replacing a roof is one of the most significant investments a homeowner can make. Our Roofing Cost Estimator helps you budget effectively by calculating the approximate costs based on your home’s footprint, roof pitch, and chosen materials. Unlike generic calculators, this tool accounts for the “waste factor” and specific labor intricacies associated with steeper slopes.
Key Factors Influencing Roof Cost
1. Roof Pitch (Steepness)
The angle of your roof significantly impacts the cost. A “walkable” roof (low slope) is cheaper to install because crews can work faster and without specialized safety gear.
- Low Slope: Easier installation, lower labor cost.
- Steep Slope (9/12+): Requires harnesses and staging, increasing labor costs by 20-40%.
2. Material Selection
Materials typically account for 40-50% of the total project cost.
- Asphalt Shingles: The most common and affordable option, usually costing between $4.50 and $7.00 per installed square foot.
- Metal Roofing: Durable and long-lasting, but costs can range from $10.00 to $14.00 per square foot.
- Slate or Tile: Premium materials that require reinforced framing, often exceeding $20.00 per square foot.
3. Tear-Off vs. Overlay
If you have only one layer of existing shingles, you might be able to layer the new roof on top (Overlay). However, stripping the old roof (Tear-Off) allows inspectors to check the decking for rot. Tearing off an old roof typically adds $1.00 to $3.00 per square foot to the job but ensures a longer lifespan for the new system.
How to Measure Your Roof Area
Most homeowners know their home’s living space square footage, but the roof area is always larger due to overhangs and slope. To get the input for “Home Footprint Area,” measure the length and width of your house on the ground, including the garage and porches. Our calculator automatically applies a pitch multiplier and a 10% waste factor to convert your ground footprint into actual roofing square footage.