AFFTA Official Fly Line Specifications & Weights

The American Fly Fishing Trade Association (AFFTA) provides standardized weights for fly lines, which you can find below. While most anglers simply use the general line weight measure when matching a line to a rod, occasionally more detailed information is useful. The table below provides the official measurements in both grains and grams. This may also be useful when trying to determine what line weight an unmarked line is, as you can simply place it on a precision scale.

Standard Single-Handed Fly Lines

(Weight is for the first 30' of line minus level tip)

Line Weight	Weight in Grains Low	Weight in Grains Target	Weight in Grains High	Line Weight	Weight in Grams Low	Weight in Grams Target	Weight in Grams High
1	54	60	66	1	3.5	3.9	4.3
2	74	80	86	2	4.8	5.2	5.6
3	94	100	106	3	6.1	6.5	6.9
4	114	120	126	4	7.4	7.8	8.2
5	134	140	146	5	8.7	9.1	9.5
6	152	160	168	6	9.9	10.4	10.9
7	177	185	193	7	11.5	12	12.5
8	202	210	218	8	13.1	13.6	14.1
9	230	240	250	9	14.9	15.55	16.2
10	270	280	290	10	17.5	18.15	18.8
11	318	330	342	11	20.6	21.4	22.2
12	368	380	392	12	23.8	24.6	25.4
13	435	450	465	13	28.2	29.2	30.2
14	485	500	515	14	31.1	32.4	33.7
15	535	550	565	15	34.3	35.6	36.9

Standard Spey Fly Lines

		Shooting Heads	Short Belly	Medium Belly	Long Belly
	Line Style	H	S	M	L
	Head Length	30'-50'	50'-60'	60'-70'	70' plus
	Weight Point	40'	55'	65'	80'
Line Weight	Increment	grains / grams	grains / grams	grains / grams	grains / grams
6		250 / 16.2	420 / 27.3	460 / 29.9	600 / 39
	50
7		300 / 19.5	470 / 30.5	510 / 33.1	650 / 42.2
	60
8		360 / 23.4	530 / 34.4	570 / 37	710 / 46.1
	70
9		430 / 27.9	600 / 39	640 / 41.6	780 / 50.6
	80
10		510 / 33.1	680 / 44.2	720 / 46.8	860 / 55.8
	90
11		600 / 39	770 / 50	810 / 52.6	950 / 61.7
	100
12		700 / 45.5	870 / 56.5	910 / 59.1	1050 / 68.2