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Fly Line to Weight Matching Chart


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We must understand that a fly line is used to move weight forward to the end of the cast, whether it be a hook, small dry fly or a heavy weighted streamer or nymph.

Fly lines are measured in weight by grains and this grain weight is used to move weight forward. For example; a 5 weight fly line weighing 140 grains is not capable of pulling the same weight thru the cast as a 210 grain 8 weight does. There are many variables to consider while casting such as wide open loops, chuck and duck, over powering or lobbing.

This chart is designed upon the ease of the cast plus normal tight loops that will cut the wind with ease. An oval back cast along with the use of the body is a must when casting weighted flies.


We will start with a 5 weight fly line, anything under that is specially designed to cast small light flies and is not suited for any type of weighted fly.


Lead Eye Weights most suitable for these line weights.

Line Ounce of weight

5 weight = 1/120, 1/80, 1/50

6 weight = 1/120, 1/80, 1/50

7 weight = 1/120, 1/80, 1/50

8 weight = 1/120, 1,80, 1/50, 1/30

9 weight = 1/120, 1/80, 1/50, 1/30, 1/24

10 weight =1/120, 1/80, 1/50, 1/30, 1/24


The above listing of course is not written in stone but if the formula is followed, long easy casts can be made. In many instances a heavier eye weight than listed can be used but it will test the caster and the capability of the rod and line.


Note" The above suggestion for choosing the right weight a fly line can move forward with ease has it variations of course, most variations comes with the style of casting being used. The most proficient style developed by Lefty Kreh where the body is involved in the cast will make casting weight more efficient.

Bob Clouser



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Thanks for posting that. That is a helpful and useful chart. One also has to consider the hook weight and materials of the fly being used. Some materials, such as many natural fibers, hold water, while many synthetics (like EP and SF) don't absorb water and shed water quickly from between fibers. A weighted fly tied with synthetics may be cast more easily on lighter line than the same size fly with marabou and hare dubbing, for example.


The grain weights for each line are recommendations for the first 30' not counting a level tip, but of course lines all vary (and AFTMA standards are in ranges anyway), and head lengths vary. So is it just the weight of the head that helps carry the weighty fly? If "grain weight is used to move weight forward" and the latter "weight' refers to a fly, then it should always be easier to cast a fly at longer distances than shorter ones (casting faults notwithstanding)--given that as the length of line outside the tip increases, so does the effective gain weight. Fly line taper matters, for purposes of turnover at different distances, and at any distance the leader taper affects turnover. Heavy flies need stiffer tippet. But the discussion as Bob puts it seems like one in which we're only casting 30' + tip.



Some say rod action matters, and that a more moderate action eases casting heavy flies. What do you guys think? I think such rods might make opening the loop easier (which is helpful to not get flies catching the line or crushing the rod blank), but that a particular cast/loop shape should dictate, and this can be accomplished with rods of both moderate and fast action. Just some food for thought...

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Way too green to comment, except to say that I am now the proud owner of some lead eyes that are quite a bit too heavy for my 5-wt rod and line. That's what happens when you have a Bass Pro gift card and try to shop for tying materials there (I got the smallest eyes they had!).


I wonder if there would be a way to modify bead chain so that it took on the right weight.


Jon H

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Guest airbornemike

Ouch! But damn I agree, that is a bunch of paper work

Rather than some obscure chart the best way to determine what your rods' limitations in combination with your casting limitations are is to actually get out & CAST.

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