Anyone has a chart of what is the inside diameter (in inch) of the hose for 3 AN, 4 AN, etc.?

 

-3AN = 3/16" ID
-4AN = 4/16" ID
....so on and so forth

Altho, it usually ends up a 1/16" smaller than that system would lead you to believe. It also depends on the kind of line you use. Aeroquip AQP and Earl's line is usually 1/16" smaller, while some Goodridge line is the same or slightly larger in ID. You just have to look at the specs in the catalogs.

 

AN diameter is designated on the OD of a hard line. The inner diameter is smaller.

 

OK. That makes more sense to me now. I can't believe it's taken me this long to find out what the real standard was.