Roof Pitch Calculator

How It Works

Roof pitch is expressed as rise over run — for example, 6/12 means the roof rises 6 inches for every 12 inches of horizontal run. To convert pitch to degrees: arctan(rise/12). The pitch factor is the key number for estimating materials: multiply your flat footprint by this factor to get actual roof area. A 4/12 pitch (common minimum) has a factor of 1.054. A 6/12 has 1.118. A steep 12/12 (45 degrees) has 1.414 — meaning 41% more area than flat. Most shingle manufacturers require a minimum 4/12 pitch; lower slopes need special membrane roofing.