The Gambrel Angle calculator computes the inner angle made by two intersecting pitches. This is common in a gambrel roof.![](https://www.vcalc.com/attachments/bb58d83c-3ebe-11ef-98f1-bc764e203090/Gambrel-Angle.PNG)
INSTRUCTIONS: Enter the following:
- (P1) Pitch 1
- (P2) Pitch 2
Gambrel Angle (B): The calculator returns the angle in degrees. It also returns the Supplementary Angle (c) in degrees. However, these can be automatically converted to compatible units via the pull-down menu.
The Math / Science
The formula for the Gambrel Angle of intersection of two right triangles is:![](https://www.vcalc.com/attachments/bb58d83c-3ebe-11ef-98f1-bc764e203090/Gambrel-Angle-Math.PNG)
B = 2π - π/2 - (π/2 -P1) - P2
where:
- B = Interface Angle
- P1 = Angle 1
- P2 = Angle 2
Note: P1 and P2 are two pitches. They are converted to radian angles.
- Pitch to Slope: This converts pitch (e.g., 4/12) to slope.
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/Gambrel-Angle.PNG)
- Pitch to Angle: This converts pitch (e.g., 10/12) to an angle in degrees.
- Rise over Run to Angle: This converts rise over run to an angle in degrees.
- Gambrel Angle: Computes the bend at the intersection of two slope as in a gambrel roof.
- Interface Angle: This computes the interface angle between two sloped surfaces.
- Interface Angle from Rise over Run: This computes the interface angle based on two rises and runs.
- Trusses Needed for a Roof: This computes the number of trusses needed for a roof based on the ridge length and truss spacing
- Roof Section Area:
This computes the surface area of an irregular shaped section of a roof.
- Gable Roof Geometries: This computes the lengths and measurements for a gabled roof based on the ridge length, pitch, span and overhang.
- Dormer Geometries: This computes the measurements for a gable dormer based on the dimension of the dormer and main roof..
- Hip Roof Geometries: This the metrics associated with a hip roof based on the dimensions.
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/gambrel-geometries2.PNG)
- Double Hip Roof Geometries: This compute the lengths of the dimensional lines where one hip roof intersects another such as in a dormer.
- Pyramid Hip Roof Geometries: This computes the lengths and dimensional lines of a pyramid roof.
- Gambrel Pitch Angles: This computes the pitch angles and rafter lengths in a gambrel roof bases on the span, total height, and height and width of the loft.
- Gambrel Rafter Lengths. This computes the upper and lower rafter lengths, attic width and total height under a gambrel roof based on the upper and lower pitch, span and loft height.
- Rafter Length: This computes the length of the rafters based on the span, pitch and overhang.
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/gable-roof-geometries.PNG)
- Corrugation Factor: This computes the material length associated with a structural length using corrugated material.
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/hip-roof-hip-dormer-lines.PNG)
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/Roof Dormer Geometries.JPG)
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/hip-roof-diagram.PNG)
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/truss-frame.PNG)
![](https://www.vcalc.com/attachments/96feb087-f03d-11ee-9b96-bc764e203090/corrugated-profile.PNG)
Roof Types
![](https://www.vcalc.com/attachments/fc48ca2c-f32b-11ed-8f09-bc764e203090/types-of-roof.PNG)
Roofing Calculators