Roof Pitch Calculator

Convert roof pitch between rise and run, angle in degrees, and slope percentage. The calculator normalizes every method to a pitch ratio with 12 inches of run, then shows angle and slope.

How to use this calculator

Choose rise and run, angle in degrees, or slope percentage. Enter the visible inputs for that method. The result shows pitch ratio, angle, and slope. If you are estimating roof materials afterward, send the pitch result to the roofing calculator. This is useful when plans give an angle but a material takeoff expects a pitch such as 6:12.

Formula

From rise and run:

$pitch\ rise = rise \div run \times 12$

$angle = arctan(rise \div run)$

For a 6 inch rise over 12 inch run, the normalized pitch is 6.0:12. The angle is 26.6 degrees, and the slope is 50 percent.

Roof measurement notes

Measure horizontal run, not the sloped rafter length, when entering rise and run. Pitch affects roofing area because steeper roofs have more surface than their flat footprint. For a basic footprint, use the square footage calculator before applying pitch multipliers. Recheck unusual dormers, additions, and mixed-pitch sections separately.