Understand and Select Right Fly Fishing Line – TruWild Life


Been using the fly line that came with the packaged starter kit you either purchased or were given? Thinking about upgrading? While everyone has an opinion on whether the fly line or the fly rod is the most critical piece of gear to improve on-stream performance, I agree with the fly liners. I believe a high-quality fly line neutralizes the limitations of most entry-level rods since a line with a slick, frictionless surface helps overcome even the most stumbling cast on a midgrade rod. Before you pick your preferred line construction technology, you must understand the basics of type and taper. 

Here are the questions you probably have:

  • Why is fly fishing line so thick?
  • What are the different types of fly fishing lines?
  • What is fly fishing line weight?
  • Which fly fishing line to use?
  • When to replace fly fishing line?
  • Does fly fishing line go bad?

Why is Fly Fishing Line Thick

At the most fundamental level, fly lines are thick because the angler casts the line, not the tiny fly at the distant end. This is the critical difference between fly fishing line vs. regular line. With regular line, the lure provides the weight. 

What is Fly Fishing Line Range

Fly lines range between 80 and 105 feet long, with the typical line being approximately 90 feet - more than you could ever cast. Add fifty yards of Piscifun fly line backing to the length, and you should never run out of line, given the typical size fish most of us are lucky enough to catch. Obviously, if you go to heaven where every trout is at least 15 pounds (or deal with steelhead or saltwater fishing), you may need more, but it will come from additional backing, not fly line.

What is Fly Fishing Line Weight

All fly line has a "weight" standardized by the American Fishing Tackle Manufacturers Association. Without getting into the intricate details, it's simpler to say that there are fifteen weights (wt), with one being the lightest and fifteen being the heaviest. Each has a stock weight, usually in the middle of the defined, acceptable weight range associated with the rating. Therefore, the overall weight of any fly line from any brand is predictable, regardless of its type or configuration.

Different Types of Fly Fishing Line

The key differences between the fly line types relate to the manufacturer's distribution of allowable weight. Line weights one through four are great for small flies. Midrange weights of five to seven are the utility lines suitable for most situations, while anything at eight or above is for large flies, windy conditions, or distance casting. What fly fishing line to use depends on where and what you fish for. Without getting into when to over or under line (using a line different from the recommended weight for the rod), just match the line to the rod. A 4wt rod should use a 4wt line. Use the higher rating to select the line on rods with multiple ratings (3/4, 5/6, etc.). Hence, a 5/6wt rod should use a 6wt line. Once you know the size line you need, you have two additional choices - floating or sinking.

Every manufacturer should be able to provide this detail on how they distribute the weight on their fly fishing line.
Every manufacturer should be able to provide this detail on how they distribute the weight on their fly fishing line.​​

Floating Fly Fishing Line

Like the Piscifun Sword fly fishing line, most fly lines float. Considering your last visit to the stream, you know it would be hard to get a drag-free drift on a dry fly with a line that consistently pulled the fly underwater. Additionally, you are familiar with adding a few split shots to the end of your tippet to push streamers or nymphs down the water column to obtain the sinking characteristic required to fish those flies. The variation in floating lines lies in the weight distribution along the length with four available choices - weight forward, double taper, shooting head, and level line.

Weight Forward

Weight forward describes a line with the most weight in the first 30 feet, followed by a gradual taper to the running line section. The Piscifun Sword fly line is a great example. Most entry-level fly fishing packages include this type of line. By pushing the weight closer to the business end, the line is easier to cast since the front-loaded weight exercises the rod to store and release energy during the cast. Remember this formula from high school physics? Force = Mass times Acceleration (f=ma). A weight forward line has more mass (matter) at the front. Higher mass with the acceleration provided by the combination of the rod flex and the "hurry up and stop" push of your forearm produces the force to move the line. With more mass at the end, getting the cast moving is more manageable – Piscifun incorporated this when they designed their fly fishing lines. In addition to customizing where the weight is, manufacturers also add their "secret sauce" to their fly line to improve slickness. For example, the Piscifun Sword fly fishing line incorporates an integrated slickness additive in the PVC layer to provide lubrication – something that provides additional distance, performance, and durability.

Look for fly fishing lines designed to be slick and easy to cast.
Look for fly fishing lines designed to be slick and easy to cast.​​

Beyond helping to get your cast in the air, being front-loaded is essential for windy conditions. The front-loaded weight makes punching the appropriately sized fly easier through a moderate breeze. The disadvantage of weight forward is it is harder to achieve a decent roll cast, but you can overcome that problem through practice and experience. Weight forward lines come in various tapers tailored to either fish or conditions. You can buy bass, trout, saltwater, redfish, and other specialty tapers. All the word "specialty" means is the manufacturer rebalanced the weight at the front end with custom tapers to the running line to account for the typical condition associated with the fish or situation. Remember, the manufacturer is dealing with a fixed amount of weight according to the standards, and all they can do is position the weight on the line to stay within the specification. Of course, this is where the manufacturing technology (coating, construction, material) comes into play to achieve additional advantages independent of the weight of the line.

Double Taper

Unlike weight forward, a double taper line places the bulk of the weight in the long middle of the line with an identical short taper to the running line on each end. Its advantage is the far end is lighter and produces less of a splash/disturbance upon landing, which is critical when dealing with heavily pressured or easily spooked fish. However, since the weight is in the middle, it is harder to cast since more line needs to get into the air than with the weight forward configuration. Novices will have a challenge achieving distance using this type of line. A double taper is easier to roll cast and better for nymph fishing. With the weight in the middle, when you bring the rod back for a roll cast, the line is balanced and better positioned for the flick that shoots the fly out. A thinner diameter line at the end is better for dry flies and nymphs since you can mend the line easier. A final, minor advantage is that either end works equally well. Once you wear out one end, reverse the line on your reel.

Shooting Head

A shooting head line is a specialty taper that pushes the bulk of the weight into a compressed area at the front of the line. Instead of gradually transitioning from taper to running line, a shooting head abruptly changes from thick to thin. The heavy front end improves your ability to cast long distances but guarantees the line will create a significant splash upon landing. Shooting heads are suitable for heavier flies or windy conditions.

Level Line

The level line, as its name implies, is a line that does not have any variations in thickness with the same diameter throughout its length. Level lines have fallen out of favor because they are hard to cast, and it has no "must buy" advantages over weight forward or double taper. Granted, the thinner diameter reduces line slap for a stealthier presentation. It is easier to roll cast than weight forward since you do not have to overcome the heavy business end. Still, the overall difficulty in casting overwhelms those two positives.

Sinking Fly Fishing Line

Sinking lines are the other major category, and they do precisely what the name implies. Instead of floating, they begin to sink at different rates depending on the rating associated with the line. Since weight standards remain in effect for sinking lines (a 4wt is still a 4wt), the manufacturers achieve the sinking characteristic by reducing the diameter of the line and coating it with heavy metal particles. You can purchase sinking lines with sink rates ranging from a 1/2 inch per second up to 10 1/2 inches per second. There are two types of sinking lines, sink tip and full sinking (lumping intermediate sinking with full sinking). A sink tip line transitions to floating between five and fifteen feet from the end and does not achieve as much penetration of the water column as a full sinking line. Since you can tie on a length of sink tip as part of your leader, you do not need to invest the money for a single-purpose sink tip line unless you consistently need the performance a dedicated line offers.

Fly Fishing Line Using Tips

Does fly fishing line go bad? When to replace fly fishing line? Thankfully, a fly fishing line lasts a long time if you condition it each season. Fly fishing line conditioner adds a coating to protect against cracking. You should examine the fly fishing line at the beginning of the season to see if any cracking is present. Typically, this will happen in the thickest part of the fly line. If it is damaged, replace it.

One final tip is to use the same brand of fly fishing line across all the weights you use. You learn how that line casts and do not have to adjust your casting stroke. For more information on tackle selection, I recommend either (or both) of these references used for most of the background supporting this article:

  • L.L. Bean Ultimate Book of Fly Fishing by Lord, Talleur, and Whitlock
  • Fly Fishing for Trout in Streams by The Freshwater Angler


Steve Moore

Steve Moore

Steve was a regular columnist for Southern Trout Magazine, where he wrote the "New Fly Guy" column to provide fly anglers with tips, techniques, and other advice between 2012 and 2019. He also wrote the "Kayak Hacks" column for Southern Kayak Fishing magazine from 2015 to 2018. 


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April 18, 2023 — Steve Moore


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