Roof Pitch Calculator
Enter rise and run to get pitch ratio, degrees, percent slope, pitch multiplier, and rafter length. Switch modes to solve for any unknown.
What is roof pitch?
Roof pitch is the ratio of vertical rise to horizontal run, expressed as X/12. A 6/12 pitch rises 6 inches for every 12 inches of horizontal distance. Most residential roofs fall between 4/12 and 9/12.
Why pitch matters for materials
Steeper roofs have more surface area than their footprint suggests. A 12/12 pitch has 41% more surface area than a flat roof of the same footprint. Always apply the pitch multiplier when estimating shingles, underlayment, and other materials.
Measuring pitch on the job
Use a level and tape measure: hold the level horizontal against the rafter, mark 12 inches along the level, then measure the vertical distance up to the rafter. That vertical measurement is your rise — giving you an X/12 pitch.
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