Roof pitch chart in degrees
Every pitch from 1/12 to 24/12, with the angle in degrees, the percent grade and the pitch factor, then common angles in degrees turned back into a pitch. The linked pitches have a page of their own with rafter lengths worked out.
Change the pitch
26.5651°≈
Multiply your run by 1.118034 for the rafter length. Hips and valleys at this pitch are in the app.
Roof pitch in degrees, 1/12 to 24/12
| Pitch | Degrees | Grade | Pitch factor |
|---|---|---|---|
| 1/12 | 4.7636° ≈ | 8.33% | 1.003466 |
| 2/12 | 9.4623° ≈ | 16.67% | 1.013794 |
| 3/12 | 14.0362° ≈ | 25.00% | 1.030776 |
| 4/12 | 18.4349° ≈ | 33.33% | 1.054093 |
| 5/12 | 22.6199° ≈ | 41.67% | 1.083333 |
| 6/12 | 26.5651° ≈ | 50.00% | 1.118034 |
| 7/12 | 30.2564° ≈ | 58.33% | 1.157704 |
| 8/12 | 33.6901° ≈ | 66.67% | 1.201850 |
| 9/12 | 36.8699° ≈ | 75.00% | 1.250000 |
| 10/12 | 39.8056° ≈ | 83.33% | 1.301708 |
| 11/12 | 42.5104° ≈ | 91.67% | 1.356568 |
| 12/12 | 45.0000° | 100.00% | 1.414214 |
| 13/12 | 47.2906° ≈ | 108.33% | 1.474317 |
| 14/12 | 49.3987° ≈ | 116.67% | 1.536591 |
| 15/12 | 51.3402° ≈ | 125.00% | 1.600781 |
| 16/12 | 53.1301° ≈ | 133.33% | 1.666667 |
| 17/12 | 54.7824° ≈ | 141.67% | 1.734054 |
| 18/12 | 56.3099° ≈ | 150.00% | 1.802776 |
| 19/12 | 57.7244° ≈ | 158.33% | 1.872684 |
| 20/12 | 59.0362° ≈ | 166.67% | 1.943651 |
| 21/12 | 60.2551° ≈ | 175.00% | 2.015564 |
| 22/12 | 61.3895° ≈ | 183.33% | 2.088327 |
| 23/12 | 62.4472° ≈ | 191.67% | 2.161854 |
| 24/12 | 63.4349° ≈ | 200.00% | 2.236068 |
Only 12/12 comes out clean, at exactly 45°. Every other row carries the ≈, because the arctangent of a rational number is irrational everywhere else.
Degrees to roof pitch
Rise per 12 is tan(angle) × 12. Roofs are framed to whole and half pitches, so the last column is the pitch to build.
| Angle | Rise per 12 | Nearest half pitch |
|---|---|---|
| 10° | 2.12/12 | 2/12 |
| 15° | 3.22/12 | 3/12 |
| 18° | 3.90/12 | 4/12 |
| 20° | 4.37/12 | 4.5/12 |
| 22.5° | 4.97/12 | 5/12 |
| 25° | 5.60/12 | 5.5/12 |
| 30° | 6.93/12 | 7/12 |
| 35° | 8.40/12 | 8.5/12 |
| 40° | 10.07/12 | 10/12 |
| 45° | 12.00/12 | 12/12 |
For any other angle, the roof pitch calculator takes degrees directly.
Reading the chart
Pitch is written as rise over twelve inches of level run. A 6/12 roof climbs six inches for every twelve it travels horizontally, which is 26.5651° and a 50% grade.
The pitch factor, also called the rafter factor, is the number to multiply a run by to get the length along the rafter. The hip and valley factors are on the roof pitch multiplier table.
