How to Calculate Roof Pitch Angle
What is Roof Pitch Angle?
Roof pitch describes slope using rise:run ratio or angle. Calculating pitch angle from measurements helps with roofing material selection and water drainage analysis.
Formula
Pitch angle = arctan(rise / run); also expressed as X:12 ratio
Step-by-Step Guide
- 1Measure vertical rise and horizontal run of roof section
- 2Calculate rise/run ratio
- 3Convert to angle or standard 12-inch run notation
Worked Examples
Input
Rise: 6 ft, Run: 12 ft
Result
Pitch = 6:12 or 26.6°
Common residential roof angle
Common Mistakes to Avoid
- ✕Measuring along sloped surface instead of horizontal/vertical
- ✕Confusing rise and run
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