Roof Pitch Calculator
Convert rise and run into pitch notation, angle and slope percent.
Vertical rise over the run.
Typically 12 inches.
Roof pitch
6/12
- Angle
- 26.6°
- Slope
- 50%
- Rise:run ratio
- 0.5
How we calculate this
Pitch ratio = rise ÷ run. Angle in degrees = arctan(rise ÷ run). Pitch notation expresses the ratio as rise-per-12-inches-of-run (e.g. 6/12). Slope percent = ratio × 100.
Example
Common mistakes
- Measuring rise and run over different horizontal spans, which skews the ratio.
- Confusing slope percent with pitch notation — they are different scales.
Frequently asked questions
How do I measure roof pitch?
Place a level horizontally against the roof surface, measure 12 inches out from the roof, then measure the vertical distance down to the roof — that's your rise for a 12-inch run.
What is a "steep" roof pitch?
Pitches above 9/12 are generally considered steep and may require special safety equipment and framing.
Related calculators
Estimates are provided for planning purposes. Actual material requirements may vary based on supplier specifications, compaction, site conditions, installation method, waste, and local code.