Beginner's Question: Line lengths and loops

I've read here about the line length proportions being 1:2:4; that agrees with what I've seen elsewhere. (Always convenient when sources agree.)

My question is:

How is that length measured?

Is it from the where the loop crosses the line (measure the "bare" line), or from the far end of the loop, or something in between?

It's easier for me to read if it's the "bare" part of the line that counts. but when I write, I start the curve in the loop immediately; so an A on a T leaves a very short "bare" line.



(by cricketbeautiful-1 for everyone)