Roof Pitch Calculator
Use our roof pitch calculator to calculate rafter length, roof pitch in degrees, roof pitch percent, and pitch as x:12 from rise and run length. Includes the roof pitch formula, how to calculate roof pitch in degrees, and a quick roof pitch angles chart.
What Is Roof Pitch?
Roof pitch describes how steep a roof is. It’s based on how much the roof rises vertically (rise) compared to how far it runs horizontally (run).
Pitch is commonly expressed three ways: angle in degrees, slope as a percent, and pitch as x:12 (how many units of rise for every 12 units of run).
This calculator uses rise and run length (in yards) to return rafter length (yards), pitch angle (degrees), pitch (%), and pitch (x:12).
Roof Pitch Formula
Roof pitch comes from basic right-triangle relationships using rise and run.
Rafter length is the hypotenuse of the right triangle formed by rise and run.
arctan returns the angle in radians, then it’s converted to degrees.
Also called slope percent.
Pitch is reported as x:12 (rise for 12 units of run).
A larger rise or smaller run creates a steeper roof.
Roof Pitch Angles Chart
Common roof pitches shown as x:12 with the equivalent degrees and slope percent.
| Pitch (x:12) | Degrees (°) | Pitch (%) |
|---|---|---|
| 1:12 | 4.76 | 8.33 |
| 2:12 | 9.46 | 16.67 |
| 3:12 | 14.04 | 25 |
| 4:12 | 18.43 | 33.33 |
| 5:12 | 22.62 | 41.67 |
| 6:12 | 26.57 | 50 |
| 7:12 | 30.26 | 58.33 |
| 8:12 | 33.69 | 66.67 |
| 9:12 | 36.87 | 75 |
| 10:12 | 39.81 | 83.33 |
| 12:12 | 45 | 100 |
How to Calculate Roof Pitch
- 1
Enter the rise (yd).
- 2
Enter the run length (yd).
- 3
The calculator computes rafter length using the Pythagorean theorem.
- 4
It calculates pitch in degrees using arctan(rise/run), pitch percent as (rise/run)×100, and pitch as x:12 using (rise/run)×12.
Frequently Asked Questions
Use Pitch(deg) = arctan(rise ÷ run) × (180/π). This calculator does that automatically from your rise and run.
Compute x = (rise ÷ run) × 12, then report the pitch as x:12.
The core relationship is slope = rise ÷ run. From that you can calculate degrees with arctan(slope), percent with slope×100, and x:12 with slope×12.
No. This tool calculates pitch and rafter length from rise and run. Roof area needs additional measurements like roof length/width (or building footprint and overhangs).
Yes. Shed roofs still form a right triangle with rise and run, so the same pitch and rafter formulas apply.