X Factor for determing leader diameter

The X factor is used to determine the diameter of leader material in thousandths of an inch and is consistent from mfgr to mfgr.  It is not a measure of leader lb test and does not vary when comparing fluorocarbon to mono.

X=11  Subtract X factor from 11 to get diameter of leader in thousandths of an inch.
ex. 3X=.008" (11-3=8)

Comparison of two common leader materials:

Seagar Grand Max fluorocarbon          Maxima ultra green mono

01X  .012"  18.5 lb________________  .012"  10 lb
0X    .011"  16.5 lb
1X    .010"  14.5 lb________________  .010"  8 lb
2X    .009"  12.5 lb________________  .009"  6 lb
3X    .008"  9.2 lb
4X    .007"  7 lb___________________  .007"  4 lb
5X    .006"  4.8 lb

When you buy a spool of Grand Max fluoro, it will have the X factor, diameter, and lb test.  When you buy a spool of Maxima or other mono, it usually does not list the X factor but lists the diameter and lb test.

I'm posting this because the "X thing" is confusing to some fishermen, especially beginning fly fishermen. Hope it helps some people.

The only fly fishing I do now is just for anadromous fish, mostly erie sthd, by "anadromous" I'm referring to great lakes fish even though technically this term applies to sea run fish.
 
When swinging I go sink tip, 20 lb mono, small black barrel swivel, tippet, length of mono leader 4 to 5 ft.   For indicator fishing, 20 lb mono, swivel, tippet, leader around 9 ft.
 
I used to fish for sea run brook trout in eastern Canada.  Used to make my own tapered leaders blood knotting sections of mono together following standard leader formula rules. For erie sthd, found that tapered leaders are unnecessary or even desirable.
 
Adding a swivel to a leader is kind of controversial, I only do this for erie or ontario fish. Main advantage to using a swivel is it's a convenient connection for attaching tippet, strong and reliable.
 
Concerning X diameter varying from brand to brand, for the type of fishing I do, it is not significant and is of little concern to me.

How does a tapered leader help you cast farther??????????????

i just notice with a tappered stiffer butt section transfereing energy to the end of the rig , no matter what fly is on the end , dry emerger , nymph etc , and regarless wether there is a indicator or split shot btween the fly line and the end of tippet , i can cast better and turn the rig over better especially on windy days even when nymphing but its just me !!