Roof Pitch Calculator
Roof pitch describes the steepness of a roof as a ratio of rise to run. This calculator converts between pitch ratios (like 6/12), angles in degrees, and slope percentages — useful for planning roofing, framing, or drainage projects.
Enter Your Measurements
Results
How to Use This Calculator
- Measure the rise (vertical height) in inches over any convenient run.
- Measure the run (horizontal distance) in inches — default is 12 inches.
- Review the pitch, angle, and multiplier results.
How Roof Pitch Calculation Works
Roof pitch is expressed as a ratio — '6/12' means the roof rises 6 inches for every 12 inches of horizontal run. The pitch multiplier is used to convert flat (plan-view) measurements to actual roof surface area. For example, a 6/12 pitch has a multiplier of 1.118, meaning the actual roof surface is 11.8% larger than the flat footprint. This multiplier is essential for ordering materials.
Formula
Pitch = Rise ÷ Run × 12 (expressed as X/12). Angle = arctan(Rise/Run) in degrees. Slope % = (Rise/Run) × 100. Pitch multiplier = √(1 + (Rise/Run)²).