Roof Pitch Calculator
Convert roof pitch between rise-over-run (x:12), degrees and percent grade, with the rafter (slope) factor.
Your inputs
Results
Pitch
6:12
- Angle
- 26.565 °
- Grade
- 50%
- Rafter / slope factor
- 1.118034
- As 1 in N
- 1 in 2
✓Exact calculation — rounded only for display
What this calculator does
Roof pitch is expressed in several ways; roofers in the US use inches of rise per 12 of run.
Formula and method
Slope = rise ÷ run; pitch = slope × 12 : 12; angle = arctan(slope); rafter factor = √(1 + slope²)
Worked example
Calculated by this tool with its default inputs:
Inputs
- I know the: Rise and run
- Rise: 6
- Run: 12
Results
- Pitch: 6:12
- Angle: 26.565 °
- Grade: 50%
- Rafter / slope factor: 1.118034
- As 1 in N: 1 in 2
How to read the results
Multiply horizontal measurements by the rafter factor to get sloped lengths and areas.
Assumptions and limitations
- Minimum pitches depend on the roofing material.
Quantities and costs are planning estimates. Add sensible allowances, and check with suppliers, carriers or professionals before buying, shipping or building.
Questions
What angle is 6:12?
About 26.57°.
Methodology and verification
- Result type
- Exact mathematical calculation (rounded only for display)
- Formula version
- 1.0
- Automated verification
- 3 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
- Editorial review
- Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.
Privacy
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