Roof Pitch Calculator
Calculate roof pitch, slope percentage, and roof angle from rise and run measurements.
Roof pitch calculator form
Results
- Equivalent US Pitch
- 6:12
- Roof Angle
- 26.57°
- Slope
- 50.00%
- Entered Measurements
- 6 in rise / 12 in run
Classification: Conventional roof pitch
Classification thresholds
- < 2:12
- Low slope
- 2:12 to < 4:12
- Low-to-moderate slope
- 4:12 to < 9:12
- Conventional roof pitch
- 9:12 to 12:12
- Steep roof pitch
- > 12:12
- Very steep roof pitch
These categories are general guidance only and do not replace local building codes, manufacturer requirements, or professional roofing guidance.
The roof rises 6 inches for every 12 inches of horizontal run. This is equivalent to a US-style 6:12 pitch, normalized to a 12-unit horizontal run.
Common Roof Pitch Table
Reference values for standard roof pitches, calculated from a 12-inch run.
| Roof Pitch | Angle | Slope % |
|---|---|---|
| 1:12 | 4.76° | 8.33% |
| 2:12 | 9.46° | 16.67% |
| 3:12 | 14.04° | 25.00% |
| 4:12 | 18.43° | 33.33% |
| 5:12 | 22.62° | 41.67% |
| 6:12 | 26.57° | 50.00% |
| 7:12 | 30.26° | 58.33% |
| 8:12 | 33.69° | 66.67% |
| 9:12 | 36.87° | 75.00% |
| 10:12 | 39.81° | 83.33% |
| 11:12 | 42.51° | 91.67% |
| 12:12 | 45.00° | 100.00% |
How to Use the Roof Pitch Calculator
- Select one measurement unit for both rise and run.
- Enter the roof rise and run in that unit.
- Results update automatically whenever a measurement or unit changes.
- Use Reset to return to the default 6 / 12 example.
Understanding Roof Pitch
Roof pitch describes steepness as vertical rise divided by horizontal run. In North America, it is commonly normalized to a 12-unit run and written as x:12. The roof angle and percentage slope represent the same steepness regardless of the measurement unit used.
- Equivalent US pitch (x:12): (Rise ÷ Run) × 12
- Angle (degrees): atan(Rise ÷ Run) × (180 ÷ π)
- Slope (%): (Rise ÷ Run) × 100
Common Roof Pitch Examples
- 3:12 — low-slope roof, about 14.04° and 25% slope
- 4:12 — low-to-moderate slope, about 18.43° and 33.33% slope
- 6:12 — common residential pitch, about 26.57° and 50% slope
- 8:12 — steeper conventional pitch, about 33.69° and 66.67% slope
- 12:12 — 45° angle and 100% slope
FAQ
- What is roof pitch?
- Roof pitch is the steepness of a roof, expressed as the amount of vertical rise for a given horizontal run. In the U.S., it is commonly written as x:12.
- How do you calculate roof pitch?
- Divide rise by run, multiply by 12 to get the x:12 pitch, and use trigonometry to find the angle and slope percentage.
- What is a 6:12 roof pitch in degrees?
- A 6:12 roof pitch equals approximately 26.57 degrees.
- What roof pitch is 45 degrees?
- A 45-degree roof angle corresponds to a 12:12 pitch, which is a 100% slope.
- What is considered a steep roof pitch?
- Pitches from 9:12 through 12:12 are generally considered steep. Pitches above 12:12 are very steep and may require specialized installation methods.