What the animation shows
The animation and the step-by-step video above use your numbers. Here is the same walkthrough written out for the default example.
What you enter
- Rise: 6 in.
- Run: 12 in.
What happens, step by step
- Hold a level flat under the roof. Its length is the run: 12 in.
- From the level's end, measure straight up to the roof: 6 in.
- Rise ÷ run × 12 gives 6 in 12, an angle of 26.57 °.
The answer: pitch is 6 in 12.
How it’s calculated
- Pitch = rise ÷ run × 12
- Angle = arctan(rise ÷ run)
- Slope factor = √(1 + (rise ÷ run)²)
Worked example
A roof that rises 6 in over 12 in of run.
Inputs
- Rise
- 6 in
- Run
- 12 in
Results
- Pitch
- 6 in 12
- Angle
- 26.57 °
- Slope
- 50 %
- Slope factor (area multiplier)
- 1.118
Assumptions and limits
- Rise and run are measured on the same plane, with the run level.
Verify the result against the applicable local code, adopted code edition, manufacturer instructions and project requirements. See our methodology.
Questions
What angle is a 6/12 pitch?
A 6/12 pitch is about 26.57°, with a slope factor of 1.118.
What is the minimum pitch for asphalt shingles?
Most manufacturers and the IRC allow asphalt shingles on slopes of 2/12 and up, with special underlayment required below 4/12. Check the shingle instructions.