OK, I'll make it simple /simpler (hopefully) with a hypothetical reel purchase with
hypothetical specs?
You live in the U.S and want to buy a reel for using say 15 AND / or 25 pound test @ ~250 and ~175 yards respectively. Of course the spool will have to be deep enough to accommodate that much MONO line, AND the assumption that the drag on this reel will be sufficient to slow down fish much larger than a bluegill.
Now the reel maker only has on their spool 0.xx mm @ xxx meters, and some have 0.xx mm @ yyy yds. which in and of itself is mixed metric and Imperial or U.S. standard.
Carrying this thought a bit further...
You also MAY want two spools, a shallower one for light test so you don't have to use 400 yards of 15 pound test and a deeper one for heavier 25 pound test line.
Lest we forget the majority of the World uses the metric system and shopping for products we are no longer confined to buying products made in or distributed for U.S. use exclusively.
Here's a sample of specs on a reel made for use outside of the U.S.
Model /Line capacity(mm/m)
Model A 0.3/150 0.37/100
Model B 0.35.125 0.4/100
Model C 0.4/120 0.45/100
Model D 0.4/150 0.45/100
So tell me how do you know what reel, (or spare spool) to buy? I'm hoping I made that clear?
So WHAT THE FREAK is .3mm/.35mm/.4mm/.45 in
pound test. So I ask again is there a conversion chart?
It can't be THIS hard to understand, or maybe all those years technical writing at IBM left me needing remedial English lessons?