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Roof pitch describes how steep a roof is, conventionally expressed as "rise per 12" — how many inches the roof rises for every 12 inches of horizontal run. It's distinct from a roofing material estimate, which is about area, not slope.
This calculator takes your rise and run measurements and converts them into standard pitch notation, an angle in degrees, and a percent slope.
How it works
Enter the rise (vertical height) and run (horizontal distance) of your roof section. The tool scales the ratio to a "per 12" pitch notation, and separately computes the angle (via arctangent) and percent slope.
- Enter rise (in).
- Enter run (in).
- Click Calculate to see your results.
Examples
A standard 6-in-12 pitch
A rise of 6 inches over a run of 12 inches gives a 6-in-12 pitch — about 26.57° and a 50% slope.
Who should use it
- Determining roof pitch before selecting compatible roofing materials.
- Converting between pitch notation, angle, and percent slope for design or permitting purposes.
Industry applications
- Residential and commercial roofing
- Architecture and structural design
Advantages
- Gives pitch in three common formats (ratio, angle, percent slope) in one calculation.
- Simple, exact trigonometric calculation.
Limitations
- Doesn't account for roof material requirements or local building code minimums for a given pitch.
Common mistakes to avoid
- Confusing roof pitch (rise per 12 units of run) with the angle in degrees — they're related but expressed very differently (a 12-in-12 pitch is a 45° angle, not 12°).
- Measuring rise and run inconsistently (e.g., mixing feet and inches) before calculating the ratio.
Best practices
- Measure rise and run in the same units (both in inches, or both in feet) before entering them, since the ratio is what matters, not the absolute units.
Tips
- Many roofing materials have a minimum pitch requirement (steep-slope vs. low-slope products) — check your pitch against your material's specifications before purchasing.