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Roofing Calculator — Estimate Materials Instantly
Calculate roofing materials, shingles, metal roofing, and roof area accurately. Get estimates for gable, hip, shed, and flat roofs.
4
Roof Types
2
Materials
10+
Pitch Options
100%
Free
Enter Roof Details
Your Results
Ready to Calculate
Enter your roof dimensions and click Calculate to see material estimates.
📏 Enter length & width📐 Select roof type⚡ Click Calculate
Roof Preview
How the Roof Calculation Works
Follow these steps to understand how your roof area and materials are calculated.
1
Footprint Area
Length × Width
e.g., 40 × 30 = 1,200 sq ft
2
Pitch Factor
√((Rise ÷ Run)² + 1)
e.g., 6/12 → √(0.5² + 1) = 1.118
3
Roof Area
Footprint × Pitch Factor
e.g., 1,200 × 1.118 = 1,342 sq ft
4
Roofing Squares
Area ÷ 100
e.g., 1,342 ÷ 100 = 13.4 squares
5
Add Waste
Total × (1 + Waste%)
e.g., 1,342 × 1.10 = 1,476 sq ft
Gable Roof Example
Inputs
length40
width30
pitch6/12
Calculation Steps
1
Footprint Area
40 × 30 = 1,200 sq ft
2
Pitch Factor
√((6/12)² + 1) = √(0.25 + 1) = 1.118
3
Roof Area
1,200 × 1.118 = 1,342 sq ft
4
Roofing Squares
1,342 ÷ 100 = 13.4 squares
Final Answer
You need approximately 13.4 squares of roofing material, about 40 bundles of shingles with 10% waste.
Frequently Asked Questions
Measure the length and width of your house at the eaves. For pitched roofs, select your roof type and pitch. The calculator automatically adjusts for slope using the pitch factor.
A roofing square is 100 square feet. It is the standard way roofing materials are measured and sold. For asphalt shingles, 3 bundles typically cover 1 square. Metal roofing is sold by panel count rather than squares.
Standard 3-tab asphalt shingles require 3 bundles per square (100 sq ft). Architectural/laminated shingles may require 4 bundles per square. Always check the manufacturer's coverage specifications.
Roof pitch is rise over run (e.g., 6/12 means the roof rises 6 inches per 12 inches of run). The pitch factor = √((rise/run)² + 1). A steeper pitch increases the actual roof surface area, requiring more materials. For example, a 6/12 pitch adds about 12% more area than a flat roof.
Standard waste allowance is 10%. Simple gable roofs may need only 5%, while complex roofs with valleys, hips, and dormers may require 15% or more. Our calculator lets you customize this.
A gable roof has two sloping sides forming a triangle at each end. A hip roof slopes on all four sides. A shed roof has a single slope. A flat roof is nearly level. Each type affects the total surface area and material requirements.
Asphalt shingles are more affordable ($80-120 per square installed) and easier to repair. Metal roofing lasts longer (40-70 years vs 15-30 years for asphalt) and costs more ($150-300 per square). Both are available in many styles and colors.
Asphalt shingles require roofing nails (about 1 lb per square). Metal roofing requires roofing screws with rubber washers (about 1 lb per square). Our calculator estimates the total fasteners needed based on your roof area.