How to Measure Roof Pitch in Degrees (4/12, 6/12, 8/12, 12/12 Conversion)
Roof pitch is usually expressed as a rise/run ratio in North America (e.g. 6/12), but solar panel installers, architects, and structural engineers often require the slope angle in degrees.
This guide explains how to convert pitch ratios to degrees using trigonometry formulas and conversion tables.
The Pitch to Degrees Conversion Formula
Since horizontal run is standard at 12 inches:
Pitch to Degrees Conversion Chart
| Pitch Ratio | Rise / Run | Angle in Degrees | Classification |
|---|---|---|---|
| 1/12 | 1 in 12 | 4.76° | Flat / Low Slope |
| 2/12 | 2 in 12 | 9.46° | Low Slope |
| 3/12 | 3 in 12 | 14.04° | Low Slope |
| 4/12 | 4 in 12 | 18.43° | Conventional Pitch |
| 5/12 | 5 in 12 | 22.62° | Conventional Pitch |
| 6/12 | 6 in 12 | 26.57° | Conventional Pitch |
| 7/12 | 7 in 12 | 30.26° | Steeper Pitch |
| 8/12 | 8 in 12 | 33.69° | Steeper Pitch |
| 9/12 | 9 in 12 | 36.87° | Steep Roof |
| 10/12 | 10 in 12 | 39.81° | Steep Roof |
| 11/12 | 11 in 12 | 42.51° | Steep Roof |
| 12/12 | 12 in 12 | 45.00° | 45° Angle |
Why Degrees Matter for Solar & Wind Loads
Solar PV Arrays
Solar panel efficiency is optimized when panel tilt equals the location's latitude (typically 25°–35° angle, corresponding to 6/12–8/12 pitch).
Drainage & Code
Roofs below 2/12 pitch (9.46°) require double underlayment or EPDM rubber membrane to prevent water ponding and wind-driven rain penetration.
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