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Roof Pitch Calculator

Calculate roof pitch, angle and slope factor from rise and run.

How this is calculated
Pitch = Rise : Run (per 12); Angle = atan(Rise ÷ Run); Slope factor = √(Rise² + Run²) ÷ Run

Assumptions used in this calculation

  • Run measured per 12 units: Pitch is expressed as rise per 12 units of run, the standard US roofing convention, regardless of the actual run value entered.
  • Simple slope only: The slope factor assumes a single, uniform pitch across the whole roof, complex rooflines with hips, valleys, and multiple pitches need to be broken down and calculated section by section.

About this calculator

The roof pitch calculator converts a roof's rise and run into its pitch ratio (x-in-12), angle in degrees, and a slope factor used to convert flat roof footprint area into actual sloped roof area.

Worked example

6 in rise over 12 in run

Result: 6/12 pitch, 26.57°

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