Roof Pitch Calculator
Convert rise and run to roof angle, X:12 pitch and rafter length. The result updates as you type, with the working underneath so you can check it.
Your details
Result
Roof pitch
21.8°
4.8 : 12
- Slope
- 40.0%
- Rafter length (with overhang)
- 4.74 m
- Roof area per m² of floor plan
- 1.077 m²
Good to know: angle = arctan(rise ÷ run)
Please note: Estimates only. Measure your actual space, buy a little extra, and check product labels, safety requirements and local building rules. Do not rely on this for structural or safety-critical work.
About this tool
Formula
angle = arctan(rise ÷ run)
Questions people ask
What is a 6:12 roof pitch?
A roof that rises 6 units for every 12 horizontal, an angle of 26.6°.
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How we calculate this
We use the standard published formula or definition for this calculation, and we show the working so you can check it.
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