Calculate Your Roof Pitch
Convert between roof pitch (rise/run), degrees, and percentage. Determine your roof area multiplier.
Understanding Roof Pitch
Roof pitch is expressed as rise over run — inches of vertical rise per 12 inches of horizontal run. A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal distance. Common residential pitches range from 4/12 (moderate) to 8/12 (steep). The pitch determines roof area (steeper = more area = more materials), drainage ability, and attic space.
The Area Multiplier
To calculate actual roof area from a footprint measurement, multiply by the pitch factor. A 6/12 pitch has a factor of 1.118 — a 1,000 sqft footprint has 1,118 sqft of actual roof surface. A 12/12 pitch (45°) has a factor of 1.414 — 41.4% more roof area than the footprint. This directly affects how much roofing material you need.
Roof pitch affects more than materials — it impacts energy efficiency. Steeper roofs shed snow faster (important in northern climates), create larger attic spaces for insulation, and allow for better ventilation. Flat or low-slope roofs (under 3/12) require special membrane roofing systems instead of shingles.
