Choosing a Fly Line that Works for You

Published on 05/28/2021 · 8 min readWait. What about weight? Fly fishing expert Jessica Scott explains how to choose the right fly fishing line weight for your next adventure.
Jesi Scott, Fly Fishing Expert
By Fly Fishing Expert Jesi Scott

Photo by Jessica Scott

Here at Curated, fly anglers often ask us what weight fly rod and reel is best for fly fishing. But the question they should be starting with is: what weight fly line is best? You’ll find that the fly rods, fly reels, and fly lines all come with an assigned weight. I would like to make one thing very clear: the weight assignment has nothing to do with the actual weight of the item. Rather, it is a classification system for us to keep things straight!

The Basics

The weight and energy of the fly line is what casts your artificial fly. The line weight is arguably the most important piece of the puzzle. However, it is all about a balance between the line, the rod, and the reel. If their weights do not match, your cast will be negatively impacted. Sure, it might cast and you might be fishing, but it probably isn’t pretty, and the line, rod, and reel are most likely not performing to their best ability.

Fly lines come in various weights, and they must be compatible with both the rod and the reel they are going to be used with. The rods and reels are designed for a specific line weight and different conditions call for different line weights. So, line weight is very important - got that?

Here’s an example for you. If you have a 5-weight fly rod - you will need a 5-weight reel and a 5-weight line. Some folks size up or down one size - meaning - if you have a 4-weight or 6-weight line you could go ahead and toss it onto a 5-weight reel on a 5-weight rod and you’ll still be good to fish, but it won’t cast as well as it could. There are some anglers who would never even consider this, while others don’t think it matters much. I suggest making sure everything is the balanced weight, especially if you are just getting going. You can mess around with mixing the weights once you are more familiar with your cast and fly fishing in general.

Alrighty, so I imagine you are still wondering why we use a “weight” to identify all of these products though it has nothing to do with the actual weight of the item. Let me tell you why. Fly lines are actually measured in grains. There are 14 grains in a gram so if a fly line says it is 240 grains it means the total weight is around 15.5 grams. But you see, nobody has time for that so they developed a scale from 0 to 15 on the weight system. Zero being the lightest and 15 being the heaviest. The fly line weight is based off the first 30 feet of the line. Typically, the 4 to 10 weight fly lines are most commonly used and the others are for quite specific scenarios.

Going Deeper

In theory, it can be pretty straightforward: the lightest fly lines for the smallest flies and fish and the heaviest lines for the biggest flies and fish. Simple, right? Well, unfortunately - there’s a little more to it than that. There are actually quite a few factors that we should WEIGH into your decision.

  • What type of water are you fishing? Saltwater? Small streams?
  • What type of fish are you targeting?
  • What’s the anticipated average size of the fish? Larger fish? Small fish?
  • What’s your budget?
  • Are you going to be fighting the wind?

I am sure you have noticed by now that there are a ton of fly lines, fly rods, and fly reels out there to choose from, but we should also try to take all of the above into consideration when picking out a setup. So, when people ask “what is the best ‘all-around’ fly rod weight?” - as you can tell there really isn’t one answer to that when so many things factor into picking the right weight for your situation.

For what it’s worth, if I had to trade my multi-rod arsenal in for just one single outfit, I would keep around a 5-weight, 9-foot rod with a 5-weight reel and a 5-weight line setup. I would feel prepared to “handle” a wide range of fly fishing scenarios with that outfit.

I trust that you are starting to understand there are many variables we want to factor into deciding the best weight fly line, fly reel, and fly rod for you. If you find yourself fly fishing in extremely different scenarios, it might be worth considering different setups so that you have a more specialized rod for certain situations. If you are fishing mountain streams one day and swinging for Steelhead the next weekend, you are going to want different outfits. But we can cross that road once you are addicted to the tug.

Photo by Jessica Scott

Know Your Weights

Below you can find a general breakdown for the weights and what they are suited for!

0 weight - 2 weight fly line

  • work best for the lightest, smallest, and quietest fish
  • not a common option
  • panfish, very small trout, or slightly larger trout but in really tight conditions
  • winds need to be almost non-existent
  • small ponds and small streams

3 weight - 4 weight fly line

  • generally smaller and lighter fish
  • mostly for small to midsize trout, and also panfish and grayling
  • not good for big trout found in large bodies of water
  • small ponds, small or midsize streams, creeks, medium sized freshwater
  • best used in areas where longer casts aren’t needed
  • could be considered for a general, all-purpose freshwater line

5 weight fly line

  • trout trout trout - if you are fishing trout, you need a 5 weight
  • variety of other species: panfish, grayling, smallmouth bass, & small largemouth
  • medium-sized freshwater
  • fine with smaller fish as well, just not as much fun of a fight

6 weight - 7 weight fly line

  • big variety of species; larger and more powerful fish
  • larger trout, panfish, largemouth bass, golden dorado, pike, salmon, redfish, carp, steelhead, bonefish
  • medium- and large-sized freshwater: big streams, rivers, and lakes
  • inefficient in targeting smaller fish or water - setup is overkill

8 weight - 9 weight fly line

  • heavier and bigger fish, mostly bass
  • can carry large flies
  • ideal for windy conditions because they are stout and heavy
  • large-sized freshwater / big streams / lakes and rivers
  • mostly freshwater and a big variety of fish species: largemouth bass, golden dorado, Northern pike, salmon, redfish, carp, steelhead, bonefish, muskie, redfish, striped bass, peacock bass, and false albacore
  • 9 (more than the 8) can be used for saltwater size tarpon, trevally

10 weight - 12 weight line

  • large saltwater and massive rivers
  • tarpon, trevally, tuna, striped bass, salmon, muskie, large carp, tarpon, peacock bass, roosterfish, mahi-mahi, giant trevally, northern pike, golden Dorado
  • heavier fishing in saltwater conditions: big fish, big flies, big winds
  • when a lighter line is not suitable and more energy is demanded

13 weight - 15 weight line

  • largest range in weight and size
  • used almost exclusively for saltwater fishing
  • used to target the largest saltwater species
  • most anglers will likely never need this sort of line
  • huge tarpons, marlin, sailfish, bluefin, mahi-mahi, tarpon, roosters, and giant trevally are likely some of the only species these lines will be utilized for

Other Considerations

The relationship between price and performance is very real when talking about fly lines. More expensive often means you’ll get better performance. However, there are lots of reasonably-priced lines that will perform well enough to meet most folks’ expectations. If you only fish occasionally, it’s not worth breaking the bank as we can purchase lines that perform well without spending tons of money. That said, if you are an avid angler, a new line and several interchangeable spools with line options can be an absolute game changer.

There are plenty more things you will want to consider when picking your line. Things such as: Do you want a sinking fly line or a floating fly line? What’s the coating and core made from? Is monofilament or multifilament best for the temperature? Should you go with double tapered, weight forward taper or level taper? And wait, about the running line, what’s the deal with that? Are you delicately presenting dry flies or are you tossing streamers? Do you need to focus on long distance casting or close and short casts? See, there’s a lot to consider when choosing the right weight line for fly fishing! We will save these topics for a different article, as I wanted to specifically discuss line weights in this one.

Photo by Adam Shick

I hope this article has been helpful in choosing the line weight that is most suitable for you. I also hope you might have learned a little bit about why that is the best option - not just because someone told you so! Another good resource is the AFFTA Approved Fly Line Weight Chart, which you can utilize by visiting here. If you have any questions, please don’t hesitate to reach out to me or another Curated Fly Fishing Expert - we are more than stoked to help you be successful on the water!

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