Roof Slope Calculator

Degrees, Pitch Ratio & Multiplier Conversion

The Roof Slope Calculator converts between three ways of expressing roof slope: angle in degrees, X-in-12 pitch ratio, and slope multiplier. A 4/12 pitch is 18.4° and has a multiplier of 1.054; a 12/12 pitch is 45° and has a multiplier of 1.414. The slope multiplier converts flat footprint area into actual sloped surface area, which is the figure you use to order shingles, underlayment, and decking. Use this tool with our Pitch Chart and Roof Area Calculator.