Roof Pitch Calculator — Rise Over Run | How to use and interpret results
Calculate slope, angle and a sloping-length multiplier from rise and horizontal run. This is geometry rather than a roofing materials or structural-design system.
- Runs in your browser
- Nothing is uploaded
- No signup; device limits apply
Numbers stay on your device. Nothing is sent to a server.
How to use this tool
Enter vertical rise and horizontal run in the same unit. Rise may be zero; run must be at least 0.01.
Results and examples
A rise of 6 and a run of 12 give 6/12 pitch, about 26.57 degrees and a multiplier of about 1.1180. That multiplier is the hypotenuse divided by horizontal run, expressing a length relationship rather than a material order.
Worked example
A rise of 6 and a run of 12 give 6/12 pitch, about 26.57 degrees and a multiplier of about 1.1180. That multiplier is the hypotenuse divided by horizontal run, expressing a length relationship rather than a material order.
Limitations
- Hips, valleys, overhangs, openings and waste are not calculated separately.
- Building requirements and load conditions are not checked.
Fields
| Field | Guidance and constraints |
|---|---|
| Rise | Accepted range: 0–100000 · Input step: 0.01 |
| Horizontal run | Accepted range: 0.01–100000 · Input step: 0.01 |
Data handling
Processing stays in the current browser tab; the site does not upload tool input for the calculation itself.
Sources
Frequently asked questions
Can I use millimetres?
Yes. Use the same unit for both dimensions.
Does 1.118 mean buying 11.8 percent more material?
Not by itself. Roof layout and waste factors are absent from this geometry calculation.
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