How do you convert roof pitch to degrees?
Convert a roof pitch to degrees with the arctangent of rise over run: angle = atan(rise ÷ 12). A 6:12 pitch is atan(6/12) = 26.57°, and a 12:12 pitch is 45°. To get percent grade instead, use (rise ÷ 12) × 100 — so 6:12 = 50%.
Source: Trigonometry (no code value) · Verify against your AHJ and the adopted code edition.
Roof pitch is written as rise-in-12: a “6:12” roof climbs 6 inches for every 12 inches of horizontal run. Because that’s just a right triangle, the angle is pure trigonometry:
angle = arctan(rise ÷ 12)
A few common pitches:
| Pitch | Degrees | Percent grade |
|---|---|---|
| 3:12 | 14.04° | 25% |
| 4:12 | 18.43° | 33.3% |
| 6:12 | 26.57° | 50% |
| 9:12 | 36.87° | 75% |
| 12:12 | 45° | 100% |
Percent grade is a different measure from degrees: it’s rise over run as a percentage, (rise ÷ 12) × 100. A 12:12 roof is 45° and 100% grade — the two scales only coincide by coincidence at that slope.
Work it out: the roof pitch converter turns any pitch, angle, or percent into the other two instantly.