How it is calculated
A sloped roof is bigger than the footprint: area = run × √(1 + (pitch ÷ 12)²) × length, for each side. One roofing square is 100 sq ft, and most shingles come in 3 bundles per square.
Example
A 40 × 30 ft house with 1 ft overhangs and a 6/12 gable roof: about 1,503 sq ft, or 16.5 squares and 50 bundles with 10% extra.
These are estimates to plan your purchase. Check measurements on site and follow the manufacturer’s instructions and local building codes.
Frequently asked questions
What pitch is common?
Many homes use 4/12 to 9/12. Shingles generally need at least 2/12, with extra underlayment below 4/12.
See also
Results are estimates for information only and are not financial, legal or medical advice. Rates, taxes and fees vary — confirm with a professional or your lender.