NPT external thread milling question

[Kasch]

I need to thread mill a 4"-8 NPT external thread on some pipe.  What diameter do I need to use for the toolpath?  Should it be the major diameter of 4.434" or 4.5" - the OD of the pipe?  At 4.5" it looks like it would be to large.  I have set the taper angle to 1.7833°, just not sure of the correct diameter to toolpath to get me close to size without putting a huge comp value in the control.

[Odin]

For external use minor diameter, and for internal use major diameter

[Kasch]

So use the minor diameter of the small end of the thread or the minor diameter of the large end?