Roofing Calculator
⚙️ Input Values
e.g. 4 (means 4:12)
📊 Result
Enter values above and press Calculate
📋 Calculation History
📖 About the Roofing Calculator
Roofing calculations start with the footprint area, then apply a slope factor to get the actual roof surface area. One roofing square equals 100 sq ft. You need 3 bundles of shingles per square.
A 4:12 pitch means the roof rises 4 inches for every 12 inches of horizontal run. The slope factor for 4:12 is 1.054, meaning the actual surface is 5.4% larger than the footprint.