🏠 Roofing Calculator
Estimate shingles, squares, and cost in seconds
How to Use the Roofing Calculator
Our roofing calculator helps you quickly estimate the materials needed for a new roof. Enter the length and width of your roof in feet, choose the roof pitch, and adjust the waste factor for cutting errors and complex roof shapes. The tool automatically calculates:
- Total roof area (adjusted for pitch)
- Roofing squares (1 square = 100 sq ft)
- Shingle bundles (typically 3 bundles per square, with waste included)
- Estimated cost based on your price per bundle
- Underlayment rolls (covers ~4 squares per roll)
What is a Roof Pitch?
Roof pitch is the slope of the roof, expressed as a ratio of vertical rise to horizontal run (e.g., 6/12 means 6 inches of rise for every 12 inches of run). Steeper pitches increase the actual surface area, which is why our calculator applies a pitch multiplier factor.
Why Add a Waste Factor?
A waste factor accounts for material loss during cutting, ridges, hips, and valleys. Standard waste factors range from 10% for simple gable roofs to 15% or more for complex roofs. Our default is 10%, but you can adjust it to match your roof's complexity.
How Many Bundles in a Square?
One roofing square covers 100 square feet. Most three-tab shingles come in bundles that cover about 33.3 sq ft, so three bundles equal one square. Architectural shingles may differ, but the calculator uses the standard 3 bundles per square for estimation.
Tips for Accurate Measurements
- Measure length and width at the roof’s eave line, not just the building footprint.
- For complex roof shapes, break the area into rectangles and calculate separately.
- If you're unsure of your pitch, use a pitch gauge or measure rise over 12 inches horizontally.
- Always round up when ordering materials – having extra bundles can save time.
Use this free roofing calculator as a starting point. For precise estimates, consult a professional roofer.
