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# Roof pitch calculator

Convert roof pitch between rise per 12, degrees, percent and measured rise and run, then size rafters, ridge height, roof area, squares and sheets.

Enter a pitch and the building size to size the roof.

The whole geometry hangs on one number, the pitch factor 1/cos(angle): plan area times the factor is the true sloping area, whatever the roof type, as long as every plane shares the pitch. Rafter lengths are geometric and deliberately exclude ridge board thickness and the birdsmouth cut, so a carpenter cuts them longer. Material minimum pitches, load limits, and structural rafter sizing are out of scope: check your local code for those.
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## More unit & math tools

- [Unit converter](/converters/units)
- [Fraction calculator](/converters/fractions)
[All unit & math tools](/converters)

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