Beginners Guide to Fly Lines

Introduction

Let’s not pretend this is just for beginners. This post began as a reference sheet after I realized all the fly line information I needed wasn’t consolidated in one place. If you've ever tried to troubleshoot a flyline-leader-tippet problem set but found yourself with 15 open tabs on 2 different browsers, the next couple articles are for you.

We’re starting with fly lines because they’re usually the first fly fishing-specific item new anglers encounter—and as we all know, there’s no fly fishing without a fly line (unless you’re trying to cast 250 yards of Maxima Chameleon, and if so… No judgement, I’m here for it.

What is a Fly Line?

Let’s dive in

What Is a Fly Line?

A fly line is a weighted, tapered line designed specifically for fly rods. It’s typically made from a braided core (nylon or Dacron) coated in PVC. Some manufacturers also use polyurethane instead of PVC. The original fly lines used horse hair and then eventually silk and were all custom made. Pretty cool fact - fly line sizes didn’t become standard until the 1930’s. I would’ve thought the UK’s NMRO office would’ve knocked that out a couple hundred years ago.. Modern fly line construction of the core and coating gives it the weight and slickness needed to load a fly rod and cast lightweight flies.

We’re sticking to freshwater, single-hand fly lines in this article. Saltwater and Spey setups deserve much more attention than I can / should give here—future posts will explore those in depth.

Fly Line Types: The Two Big Categories

Fly lines come in two major types—floating and sinking—with several subtypes that fine-tune their performance. Here's the breakdown:

Floating Fly Lines

These lines stay on the water’s surface and are ideal for dry flies, nymph rigs, and general purpose streamer fishing.

Common Subtypes:

  • Weight Forward (WF)
    The most popular floating line. It has a heavier “head” that helps load the rod easily. Perfect for beginners and a fantastic choice for an all purpose fly line.
    Example: WF5F = Weight Forward, 5-weight, Floating

  • Double Taper (DT)
    Balanced and reversible, this line is great for delicate presentations. It lacks the aggressive taper of WF lines but excels in finesse situations. Ideal for roll casting and short, accurate presentations.

  • Shooting Taper (ST)
    A variation on WF with a heavy head and a thinner running line for longer casts and a “punchy” feel to your first cast, limiting the need for false casting. This type of line has absolutely no finesse to it, so it’s better in the surf. This also differs from most other fly lines in that the head portion of the line is often a completely separate line from the thin running line, often joined with welded loops. There’s also a whole host of different types of shooting heads, that are probably best covered in another section.

  • Level Line (LL)

    A specialty line typically used in euro nymphing rigs. Basically just gives enough weight to the rig to keep it from sliding back thru the eyes. Absolutely no taper or casting power to it.

  • Triangle Taper (TT)

    Gives it a shooting head characteristic, great for roll casting because the line just wants to run. Great for small water.

Sinking Fly Lines

Designed to get your flies below the surface. A very early mistake I made was assuming you had to nymph with these lines - using a floating line is perfectly fine for most rivers and streams. For most rivers, sinking fly lines are utilized as streamer or wet fly options. On stillwater a sinking line excels with getting nymphs and wet flies deep as well. I elected to not go into sink rates and densities here, I feel I wouldn’t be able to do it justice without dedicating an entire post to it.

Common Subtypes:

  • Sink Tip Line
    The tip sinks while the rest floats. Good for small rivers where control and precision matter and getting to a certain depth quick. You get a slightly different presentation with the floating section of the line - great for wet flies or as a streamer line.

  • Full Sinking Line
    The entire line sinks. Many prefer these options for streamers and stillwater fishing. These are broken down further by sink rate:

    • Full Sink: Fastest sinking option and good for deep stillwater or fast moving water where you’ve got to get deep fast.

    • Intermediate Sink: Slower sink rate for mid-column (1-4’) or keeping flies at a specific depth for longer periods of time. Ideal for slower moving water but a perfectly acceptable general streamer line.

    • Slow Intermediate: A gentler version of intermediate sink allowing greater control. Typically used on slower moving water or flats.

We’ll cover sinking line specs, densities, and sink rates in more detail in a dedicated future post.

So now you have your line type picked out. What now? Matching Fly Line to Your Rod

The most important rule: match your rod weight to your fly line weight. The line weight (3WT, 4WT,5WT,8WT,etc.) is a measure of the weight of the line in the first 30 feet measured in grains. What this means is - a higher line weight, say 8WT, is heavier than a 4WT, even if it’s the same line type. Since line and rod weights are standardized across the industry, they are both manufactured for optimal performance with its counterpart.

Example: If you own a Scott FS 7’2” 3-weight, your ideal match is a 3F (3-weight floating) line.

Can You Overline or Underline?

Yes, but it’s a matter of personal style and tactical needs.

  • Overline: Use a heavier line (e.g., 6WT on a 5WT rod) to cast large flies or fight wind.

  • Underline: Use a lighter line for faster rod action.

It’s doable, but not always recommended unless you’re aiming for something very specific.

What Is Fly Line Backing?

Backing is the line that connects your fly line to the reel. It's typically made from braided Dacron, gel-spun polyethylene, or similar materials. It allows you to use the full 90’ of your fly line, seamlessly connect your rig to your spool and reel, and provides an assurance against shock loading your line against a hard stop.

How Much Backing Do You Need?

  • Fill your reel until there's about 1/8" of clearance from the top of the spool.

  • Too much backing and you’ll introduce friction between your fly line and reel.

  • Too little and you’ll have an empty reel and struggle to maintain control of the line. Not to mention the risk of shock loading your line with a hard running fish.

Pro Tip: Want perfect tension and capacity? Make your backing to fly line connection, load the fly line first and add backing until the reel has that 1/8” gap, then pull it all off and install your backing to the spool and load it up. Some reels also have a spec for the backing footage, the Lamson Liquid 5 reel calls for 100 yards of 20# backing.

Take note of the gap

This is a great example of a well lined fly reel.

Final Thoughts

Understanding fly lines is a foundational skill in fly fishing. Whether you're starting fresh or filling in knowledge gaps, knowing how to pick and pair a fly line with your setup saves time, frustration, missed fish, and ever more, money.

Next up: Leaders and tippets—the workhorses of your fly rig.