Roof Pitch Calculator
Convert roof rise and run into pitch, angle and slope factor.
Roof pitch describes how steep a roof is. This tool converts between the 'rise in 12' notation, the angle in degrees, and the slope factor used to turn a flat footprint into actual roof area.
The math behind it
Pitch is the rise over a 12 in run, e.g. '6/12'. Angle = arctan(rise ÷ run).
Slope factor = √(rise² + run²) ÷ run — multiply a roof's flat footprint area by this to get the sloped surface area.
Worked example
Rise 6 in over run 12 in → pitch 6/12, angle 26.57°, slope factor 1.118.
FAQ
What is a 'good' roof pitch?
4/12 to 9/12 is common for shingled roofs; below 2/12 needs special low-slope materials.