Understanding Fly Line and Weights

Balancing fly line, rod, and reel provided by Scientific Anglers.


Assembling a balanced fly fishing rig is as easy as matching the numbers on the fly line to the numbers on the fly reel and fly rod.

For instance, you would match an Ultra 4 5-weight fly line with a 5-weight fly rod, and you'd spool it on a 4/5/6 fly reel.

Lower numbers & ndash weights 2-6 & ndash denote smaller gear best suited to trout and panfish. As the numbers rise, so does the gear's ability to cast larger flies for bigger game fish. Weights from 11-15, for instance, are built for big tarpon, billfish, and other large saltwater species.


Read the fly line label to determine which fly line best meets your needs.
Most fly lines have informational labels that give you the basic specifications for that line. Below is an Ultra 4 label as an example. And please remember & ndash no matter which fly line you choose, it is essential to match the fly line weight with the rod weight to ensure balanced, reliable fly fishing performance.
Read the fly line label
Species Line Leader/Tippet Backing Reel Rod Top Flies
General Freshwater Weight: 4/5/6/7
Taper: WF or DT		 7X-0X
(2 lb - 10 lb)		 Strength: 20 lb
Amount: 50 yd		 Size: 4/5/6/7
Drag: Disc or Click		 Weight: 4/5/6/7
Length: 8' - 9.5'		 Dries, Wet Flies, Nymphs,
Terrestrials, Streamers
Trout Weight: 4/5/6
Taper: WF or DT		 7X-0X
(2 lb - 10 lb)		 Strength: 20 lb
Amount: 50 yd		 Size: 4/5/6
Drag: Disc or Click		 Weight: 4/5/6
Length: 8' - 9'		 Dries, Wet Flies,
Nymphs, Streamers
Panfish Weight: 4/5/6
Taper: WF or DT		 7X-0X
(2 lb - 10 lb)		 Strength: 20 lb
Amount: 50 yd		 Size: 4/5/6
Drag: Disc or Click		 Weight: 4/5/6
Length: 8' - 9'		 Small Poppers, Nymphs,
Terrestrials, Streamers
Bass Weight: 7/8/9
Taper: WF		 8 lb - 12 lb Strength: 20 lb
Amount: 50 yd		 Size: 7/8/9
Drag: Disc		 Weight: 7/8/9
Length: 8.5' - 9.5'		 Large Poppers,
Deceivers
Pike Weight: 8/9/10
Taper: WF		 8 lb - 20 lb
with wire bite guard		 Strength: 20 lb
Amount: 100 yd		 Size: 8/9/10
Drag: Disc		 Weight: 8/9/10
Length: 8.5' - 9.5'		 Large Specialty Pike Flies,
Large Poppers, Divers
Salmon Weight: 8/9/10
Tapers: WF, DT, ST		 8 lb - 16 lb Strength: 20 lb
Amount: 100 yd		 Size: 7/8/9
Drag: Disc		 Weight: 7/8/9
Length: 8.5' - 9.5'		 Streamers,
Nymphs, Eggs
Steelhead Weight: 7/8/9
Tapers: WF, DT, ST		 8 lb - 16 lb Strength: 20 lb
Amount: 100 yd		 Size: 8/9/10
Drag: Disc		 Weight: 8/9/10
Length: 9' - 10'		 Streamers,
Nymphs, Eggs
General Saltwater Weight: 7/8/9/10
Tapers: WF, ST		 8 lb - 20 lb Strength: 20 lb
Amount: 175 yd		 Size: 7/8/9/10
Drag: Disc		 Weight: 7/8/9/10
Length: 8.5' - 9.5'		 Crazy Charlie's, Crabs,
Shrimp, Deceivers, Minnows
Striped Bass Weight: 8/9/10
Tapers: WF, ST		 10 lb - 20 lb Strength: 20 lb
Amount: 175 yd		 Size: 8/9/10
Drag: Disc		 Weight: 8/9/10
Length: 8.5' - 9.5'		 Deceivers,
Deep Minnows
Bonefish Weight: 7/8/9
Taper: WF		 8 lb - 20 lb Strength: 20 lb
Amount: 175 yd		 Size: 8/9/10
Drag: Disc		 Weight: 8/9/10
Length: 8.5' - 9.5'		 Crabs, Crazy Charlie's,
Deceivers, Minnows
Tarpon Weight: 10/11/12
Taper: WF		 10 lb - 20 lb
with shock tippet		 Strength: 30 lb
Amount: 250 yd		 Size: 9/10/11/12
Drag: Disc		 Weight: 9/10/11/12
Length: 9'		 Large Saltwater
Poppers, Minnows
Billfish Weight: 12/13/14/15
Tapers: WF, ST		 20 lb
with wire bite guard		 Strength: 30 lb
Amount: 250 yd		 Size: 12/13/14/15
Drag: Disc		 Weight: 12/13/14/15
Length: 9'		 Large Specialty Billfish Flies,
Large Saltwater Poppers