For Understanding of NPT thread

I am using NPT Thread Calculator to calculate the NPT thread dimensions.

But I am confused

For example ¼ NPT thread

Drill size is 7/16” but how long is deep?

Thread Size is ¼ with 18 TPI but what is the total depth of the thread?

My understanding for example ¼ NPT will include

NPT total depth = Hand Tight Threads + Wrench Tight Thread

= 0.2278 + 0.1667 = 0.3945

If total depth = 0.3945

Drill 7/16” depth can be 0.6945” for clearance only (flexible)

Is this the way to calculate NPT machining dimension?

The value 0.2278 will be inspected using the plug gauge?

Thanks,