Line Classification: Old vs New

"Old vs. New" Line Classification

Prior to 1961, fly lines were distinguished by a letter code that corresponded to its diameter. Beginning in 1961, lines were classified by their "weight". This system is based upon the weight in grains of the "working portion" of the line. For practical purposes, this is the first 30' of a fly line.

The old letter code was a cumbersome system, and one you do not need to know down to the "nitty-gritty." What you do need to learn and understand is the relationship between the various fly line sizes.

The chart below is a "conversion table" that shows the "old" coding system vis-a-vis the current classification method.

Old classification		New classification	Line "weight"
(representing diameter)		(representing "weight")	weight in grains*
double taper	weight fwd
IGI	IGJ	3 wt.	100
HFH	HFG	4 wt.	120
HEH	HEG	5 wt.	140
HDH	HDG	6 wt.	160
HCH	HCF	7 wt.	185
GBG	GBF	8 wt.	210
GAG	GAF	9 wt.	240
G2AG	G2AF	10 wt.	280

* there are 437.5 grains in 1 oz. (so a 3 wt. line @ 100 grains "weighs" .229 oz. for the first 30 feet of its "working portion")

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