Fly Fishing Lines | Understanding Fly Fishing Line Types and Applications

When anglers start fly fishing, they often focus on sinking their time and money into finding the right rod. That’s understandable rods have the curb appeal few other pieces of gear do, but what’s often overlooked is the importance of fly line to how your rod performs. With the right line, any rod can come alive and almost sing as you cast; the wrong line can make it feel like either a broomstick or wet noodle. No matter how much you spend on your first rod, that’s not what you want to feel when out on the water. A lot of newer fly anglers feel intimidated by the sheer amount of fly line choices available. Where beginners are usually steered towards a 9’5wt or 6wt fly rod, there’s far less guidance on what line to buy, and more importantly, why you should buy that fly fishing line.

Line Weights

Fly lines are classified by their weight, just like fly rods are classified by the weight of line they’ll cast. For example, a rod marked as a 9’5wt will fish best with 5wt fly line. The American Fly Fishing Trade Association (AFFTA) sets the standards for fly line weights, and rod builders try to create rods that align with those designations. A standard weight-forward 5wt line should weigh 140 grains. But here’s where things get a bit tricky: because modern fly rods are so much faster than rods from the 70s and 80s, most lines are made a half-weight heavy. For example, a lot of current 5wt lines weigh in around 150-155 grains, which is 10-15 grains heavier than AFFTA standard.


This might seem a bit too in-depth for the average fly angler, but here’s why understanding line weight matters:  

  • Fast-action rods require more weight to properly load energy into the rod, which creates the loops in your fly line that drive a fly toward your target  
  • Medium-to-soft action rods don’t need as much weight to load with the right amount of energy  
  • Fast rods are generally used for nymphing and streamer fishing, and throwing bigger dry flies 
  • Medium-to-soft rods are generally used for dries size 16 down to 22 or 24  

As mentioned above, most anglers will start out with a 9’5wt rod with a faster action. These rods are beginner-friendly, and work well in nearly every angling situation you’ll encounter.  

However, if you live in an area dominated by small freestone streams and spring creeks, you may opt for a 3 or 4wt to better present smaller flies to wary trout. Conversely, those living close to big waters like the Missouri River, North Platte, Madison, Rogue, Deschutes, and others, will want a faster rod that’s able to cover more water and push bigger flies further.  

Your choice of line should reflect both what weight of rod you own and what action that rod is.  

  • True-to-weight lines are those manufactured to AFFTA standards, and are the best choice for medium-to-soft action rods used for smaller flies and delicate presentations.  
  • Half-weight or full-weight heavy lines are built 10 to 20 grains above their printed weight rating. These are the lines you’ll want to look at if you’re fishing a faster rod with bigger flies and the need to cover water.

Line Tapers

Line weight is a fairly easy concept to understand: you want to match the weight of the line to the action of your rod and style of fishing. Where things can start going over your head is by diving into a line’s taper.  

Understanding line tapers matters because:  

  • Line taper affects fly presentation 
  • Line taper impacts your ability to perform certain casts, i.e., roll casts and reach casts  
  • Some rods fish better with one taper over another  

So what exactly is a fly line taper?  

A taper refers to the head of a fly line, which is almost always the first 30 feet of line. This is also the section that gives a line its weight rating (i.e., the first 30 feet of a 5wt line will weigh between 140 – 160 grains).  

The head of a fly line is made up of three parts:  

  • Front taper: this is the first 2 – 11 feet of most fly lines, and gradually increases in diameter. The front taper exists to dampen energy on your forward cast in order to deliver the best fly presentation possible. For example, a line designed for small dry flies will have a long front taper. This extends the size of your loop, increasing the time it takes to unfurl, and dissipating energy before landing softly on calmer water. Shorter front tapers are meant for big flies that demand to be loaded quickly and shot with minimal false casting – like streamers or bass bugs.  
  • Belly: this is the chunk of line between your front and rear taper, and it’s almost always level. This means it’s the same diameter throughout its entire length.  
  • Rear taper: this is the end of a fly line’s head, and its length varies widely from line to line. The rear taper exists to transfer energy from the belly to the running line to aid in casting longer distances.  

This is an example of a line with an aggressive head design, and consequently an aggressive, heavy taper. It’s built for throwing big bugs towards the banks of rivers, or out into lakes.

PHOTO: The darker line is the head and the orange line is the running line.


PHOTO: Meanwhile, this line has a true-to-weight head design and light taper, making it ideal for smaller flies on calmer water.

Just as the weight of your line affects your rod’s performance, so too will the taper of the line you choose to fish with.  

Tapers Within Tapers

It’s worth noting that there are two main types of tapers:  

  • Weight-forward: This is by far the most common type of line taper. The entirety of the line’s AFFTA weight is contained in its head, which is usually the first 30 feet of a line. These lines put all the weight “forward” in the line to more quickly load fast-action rods 
  • Double-taper: formerly popular, double-taper lines are used for slow rods like fiberglass, bamboo, and antique graphite. A double-taper line distributes its weight throughout the entire line, with very short front and rear tapers. Since the entirety of the line is the same diameter and weight, double-tapers roll cast exceptionally well. They also load fully-flexing fly rods more effectively than a weight-forward taper.  

So which fly line do you need?

Now we’re to the most important question – what fly fishing line do you need? 

Take the following factors into account: 

  • Rod Action: if you’re fishing a faster rod, you’ll want a line with both a more aggressive taper and heavier weight. This will load your rod more effectively and bring out the best performance in the rod. Softer rods fish better with gradual tapers and AFFTA standard weights.  
  • Common Fishing Situations: if you know you’ll be on small spring creeks and streams, you’d do well with a true-to-weight weight-forward or double-taper line with a slight taper design. If you spend the majority of your angling time on bigger water, you’ll want line to match.  
  • Desired Presentations: lastly, you need to take into account how you want your flies presented to fish. Small spring creeks and streams aren’t necessarily always long, glassy runs in high-mountain meadows. Many are full of pocket water, which doesn’t require as delicate a presentation. So it’s entirely possible to own a medium-action rod, fish primarily small streams, but use a heavier weight-forward line because it’s easier to shoot casts into tight pockets. Conversely, if you want to fish streamers in big water, a heavy taper that shoots flies with minimal false casting is your best bet.  

The world of fly lines and tapers might seem overwhelming at first, but it’s worth the learning curve. As you figure out which tapers and weights work best with your desired approach, you’ll be surprised at how much better your fly rod performs, and by extension, how many fish end up in your net.

Want to learn more about fly fishing? Fly Fishers International Master Casting Instructor, Dayle Mazzarella now offers exclusive “how to fly fish” content through the “Fly Fishing Coach International Course”. The course is an online video-based set of fly fishing lessons spanning 5 different chapters of instruction. Whether you are a beginner, or an avid fly fishing enthusiast, there is information and lessons to be learned. 

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