Roofing Calculator
Estimate roofing materials including shingles, underlayment, and squares. Get accurate measurements for any roof pitch.
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Roofing Guide
Roofing is measured in squares — 1 square = 100 sq ft. Standard shingles come 3 bundles per square. The pitch factor adjusts for roof slope; steeper roofs need more material.
- Add 10% for waste, starter strips, and ridge caps
- Underlayment: 1 roll covers approximately 4 squares (400 sq ft)
- Steeper roofs require more safety equipment and may cost more to install
Frequently Asked Questions
How many shingles do I need for my roof?
Roofing is measured in squares (1 square = 100 sq ft). Standard shingles come 3 bundles per square. Multiply your roof area by 3 and divide by 100 to get the number of bundles needed.
What is a roofing square?
A roofing square is a unit of measurement equal to 100 square feet of roof surface. When you hear a roofer say a 20-square roof, they mean the roof covers 2,000 square feet.
How do I measure my roof pitch?
Roof pitch is measured as inches of rise per 12 inches of run. For example, a 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. You can measure this with a level and a tape measure.
Should I install new shingles over old ones?
It's generally not recommended to install new shingles over old ones. Removing old shingles allows inspection of the roof deck, ensures proper ventilation, and extends the life of the new roof.