Diameter of braided line?
- Taradiddle!   

For a braided lines (BL) there is no and there can not be the diameter. It is possible to speak only about a sectional area, the thickness.
And whether it is possible to talk about "a thickness of BL, appropriate to the some diameter of mono line (ML)"?

How to determine this correspondence? On equality of a sectional area or on containment on a spool? Essence in that BL thickness and containment on a spool poorly correlate.
On a photo is rotined Stream, which one is called as "0.16mms dia". An obvious case of absurdity of "diameters" in general and marks in particular.
The 3-strands line in itself plane. If absolutely slightly to clamp it in jaws of a calliper, it is received by height of 0.1mms, and width runs up approximately to 0.7mms.
On a spool with cross winding (*) it will keep itself if not as 0.1mms ML, then "not thicker", than line of 0.15mms dia: in a split of 0.2mms the cord dangles around absolutely free. That is the layers will have the same quantity of line turns and the height of layers will be about these 0.15mms. At that its actual thickness (total, up to the limit squeezed sectional area), - I estimate, - is about 0.05 square millimeters. And for 0.15mms dia ML - 0.018 square millimeters, in 2.8 times less (an illustration see at Appendix).
(*)  Step of a cross winding practically always is more than 0.7mms. For known for me baitcasting reels the step of cross winding is 0.85-2.8mms, usually it is 4-5 of maximum dia of recommended  mono lines.
In other words, if on the same spool it is possible to contain 100m of a ML or 100m of this line, the BL actually will be in 2-4 times thicker by a sectional area.
Here one reason of BL's "super strength". And, in my opinion, the basic reason (second, and less significant, - for a BL's the discontinuities, microflaws of a material have a less effect: for a ML they will resulted in a breaking in this place, and for a BL will be broken or rather will be spread only some fibers).
By the way, a sectional area of 0.05 square millimeters has the ML of 0.26mm dia, the "0.16" did not lie by near.
Certainly, it is an extreme case - 3-strands line. The BL's with 4, 6, 8 strands are "more round", up to a 7:1 ratio it is hardly to crumple with easy. Especially of dense braiding...
You are sure? I too so thought.
Here a 6-strands 30lb Stren Super Braid of rather dense braiding, on it also "8lb dia .26mm" is written.
Without ceremony it is compressed up to the same 0.1mms. And too is freely dragged in a slot of 0.2mms... First time from a bobbin it is balked a little, then go with a run.
  •   The sectional area of the BL is informative. But then it is necessary to agree, to standardize - at what efforts of compression to gauge this section: its account highly depends on an effort of compression. But to cause the manufacturers to agree - it is the Utopia... Furthermore at exploitation the BL's in a free state "in space" and on spools swell and behave variously.
  •   As the objective and useful knowledge in the given situation is seen the knowledge of quantity of fibers (Dyneema, Spectra, PE). Provided that they "standard". Or - that there is a restricted quantity of types of fibers. I hope, we shall clarify this... Quantity of strands, density of a braiding and some other qualities too influence properties of a cord, but nevertheless I figure, that actual strength and thickness of braided lines in the much greater degree are determined by total of fibers.
    Appendix.  Winding on a spool in a sectional view
    The same step of cross winding S and layer height H. It means on a spool will be contained ML or BL lines of identical length. Though a braided line approximately in 2.8 times thicker than a mono line.
    The big arrows rotin an interleft direction of cross winding.
    Actually the winding is more similar to a "turn to turn" type, than to the rotined dilute regular layers, volume of a spool is filled even by mono line on 80-85%. Weight of the wet braided line and mono line on the same spool is about the same.


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