Roof Pitch Calculator
Enter rise and run to get the roof pitch, angle, and slope factor.
Work out any roof pitch
Roof pitch describes how steep a roof is, and it drives everything from rafter length to how much material the sloped surface actually needs. Enter the rise and run and this returns the pitch ratio, the angle, and the slope factor.
A 6/12 pitch works out to about 26.57 degrees with a slope factor of 1.118, meaning the real roof area is roughly 12% larger than its footprint. Steeper pitches raise both figures.
Accurate and private
It computes the angle from the arctangent and the slope factor from the hypotenuse, all in your browser with nothing uploaded.
Frequently Asked Questions
How is roof pitch expressed?
As rise over run, usually per 12 units of run — a 6/12 pitch rises 6 inches for every 12 inches horizontal.
What is the slope factor?
The multiplier that converts the flat (plan) area into the actual sloped roof area: √(rise² + run²) ÷ run.
How do I get the angle?
The angle is the arctangent of rise divided by run; a 6/12 pitch is about 26.57 degrees.
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