Roof Pitch Calculator
Pitch is rise over run, shown as x:12, degrees, and percent. The area factor is hypot(1, rise/run). Multiply a plan area by that factor. Estimate only, not code approval.
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How to convert roof pitch to degrees
- Enter rise and run in the same unit, such as 6 and 12 for a 6/12 roof.
- Read pitch in 12, the angle, and percent slope.
- Use the area factor to scale a rectangular plan toward roof surface.
- A full gable takeoff with length and width is the roof area page. Not code approval.
Roof pitch
Rise over run for a roof slope
| Pitch in 12 | (rise/run) × 12 : 12 |
|---|---|
| Angle | atan(rise/run) in degrees |
| Percent slope | (rise/run) × 100 |
| Area factor | hypot(1, rise/run) |
| Plan to roof | plan area × area factor |
| Advice | Estimate only. Not structural design or code approval. |
How pitch, angle, and area factor are computed
Ratio is rise divided by run. Pitch in 12 multiplies that ratio by 12. Angle is arctangent of the ratio. Percent slope is the ratio times 100. Area factor is the hypotenuse of 1 and the ratio, equal to hypot(run, rise)/run.
Estimate only
Hips, valleys, and overhangs are not in this factor. Truss stamps and snow load are not computed. Not code approval.
Use cases
Reading a 6 and 12 stick, converting pitch to degrees, or grabbing a factor before you measure the plan. A math line between two points is the slope calculator, a different job.
Limits
Run must be greater than 0. Rise can be 0 for a flat factor of 1. CZNull does not receive the numbers.