Roof Pitch Calculator
Convert between roof rise/run, angle in degrees, and pitch percentage. Calculates actual roof surface area and rafter length.
LIFESTYLEConvert between roof rise/run notation (e.g. 6:12), angle in degrees, and pitch percentage. Plus actual roof surface area and rafter length when you provide the building footprint - essential for ordering shingles, calculating snow load, or building rafters.
Pitch math: angle θ = atan(rise/run); pitch % = (rise/run) × 100; slope multiplier = √(rise² + run²) / run. Actual roof area = footprint × slope multiplier (a 6:12 pitch has a 1.118 multiplier, so a 1200 sq ft footprint yields 1342 sq ft of actual roof surface). Rafter length from ridge to eave = √((width/2)² + ((width/2)·rise/run)²). Classifications: under 1:12 is flat (membrane roofing required), 4:12-8:12 is conventional (shingles OK), over 8:12 needs steep-slope safety equipment.