Birdsmouth Cut Calculator

Geometry of a horizontal seat and vertical heel cut. Does not determine permitted notch depth,connection strength or building-code compliance.

Your workbenchInputs are not stored

Result

Enter your values and run the tool to see your result.

Check the units, enter your values, and run the tool. Results follow the assumptions and method below.

Rafter slope angleatan(pitch/12)*180/pi

Vertical heel-cut heightseat*pitch/12

Notch depth perpendicular to rafterseat*sin(atan(pitch/12))

Remaining perpendicular depthdepth-seat*sin(atan(pitch/12))