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Choosing a Fly Rod Part 1:  Line Weight and Length

Choosing a Fly Rod Part 1: Line Weight and Length

This article is the first in a series that will help serve as a guide when choosing a new fly rod. The goal here is to tackle a number of questions and considerations that we see here at TCO when our customers and clients are shopping for a fly rod. In doing so, these articles will also provide a good explanation for understanding fly rods in general if you’re new to the game. It is worth noting that it’s hard to discuss fly rods in vague terms, as it ignores a lot of nuance in how rods are designed and some of the finer differences that can matter quite a bit. I’ll try and provide some basics that apply to the most common applications. Understand that all fly rods have some level of versatility and the angler behind that rod will bring a unique set of skills and preferences that might veer from the statements below. Regardless, the information below is not only useful to consider when making a purchase, but will also help you to understand the equipment you may already have. I’ll be focusing this discussion on single hand fly rods, as the two handed world is an entirely different story. 

Line Weight

Line weight is probably the first thing we consider when determining which fly rod will work for our fishing. Along with length, line weight is the predominant factor for which applications a fly rod can be used for. Typically, line weight corresponds to the weight of the fly line it is designed to cast. This means a heavier rod which uses a heavier line can cast a heavier or wind resistant fly with greater ease. The size of the fly or rig we can cast is therefore the main consideration when choosing a line weight, regardless of the size of the fish. This especially holds true in fresh water. Sometimes we need a bigger rod for a bigger fish, but in most typical situations, we are more worried about the flies we are casting versus what species we are fishing for. For example, you may be able to land a largemouth bass with a 5 weight rod with no risk of breaking it, but bass are known to take larger food sources. This means you could use an 8 or even a 9 weight to cast the largest of bass flies that a five weight would struggle to cast. Despite not needing a rod of that size to land the fish, having a rod that can handle casting the fly itself will improve your experience. Heavier line weights also generate more energy and line speed in a cast, making casting into the wind and longer casts much easier. This is why heavier rods are used for saltwater even if the flies may be something that could be casted on lighter setups. 

This brown trout was caught using a very heavy stonefly nymph. I prefer a 6 Weight when fishing heavy nymph rigs under a strike indicator. 

How do rod manufacturers determine line weight? The fly fishing industry uses a standard system that is based on how many grains a fly line weighs in its first 30 ft. In simple terms, a rod is designed to cast a fly line that weighs a certain amount. If a line were to be too heavy, it would bend the rod too much during casting making it hard to manage when casting further, creating a clunky feel to the cast. If a line is too light, it will not bend the rod enough, making it difficult to use when casting in close and will not give you as much “feel” when casting. Companies do not always perfectly follow these standards, especially when they are making lines and rods for more niche purposes. Without getting too far into the weeds about discussing fly lines, understand that most rods can handle a range of fly lines that may be a few grains heavier than the industry standard, with some rods that are designed for that very purpose. Sometimes you will see people opt to use a fly line that is a full size heavier than suggested for a rod. This might be because they are looking to get a different type of use out of the rod such as very short range casts, or they want to feel the rod load and bend more easily when learning to cast. 

Chris Frangiosa shows off a beautful Permit. When flats fishing, windy conditions and long casts often call for heavier line weights. 


Though line weight tells us a lot about how a rod can be used, it is not the only factor. Rod length coupled with line weight is a crucial piece of the puzzle and can change the equation dramatically. For example, a 7 foot 3 weight and a 10 ft 3 weight are not remotely used for the same purposes. Though they are both 3 weights, the added length changes both how the rods cast, and what applications they are best suited for. In some cases, length is just personal preference while in other situations it can change everything. 

Rods less than 8’6’’ tend to be specialty rods for smaller water and lighter line weights. They have a casting sweet spot that is somewhere under the 40 ft range. In smaller streams, it is common to never make a 40ft cast in a day of fishing. Rods this short will struggle to mend line on the water, and have less reach to hold line off the water. The trade off is that they will load and be more accurate in close, and can be a little easier to manage in tight quarters. Most of the time, these shorter rods are dry fly oriented tools that lack the versatility or their longer counterparts. In some cases, the shortest of rods are not always used out of necessity or utility, but because they can be just plain fun on smaller streams. 


When fishing for small native brook trout, short light rods are not only more practical in many cases, but are more fun to use.

 Rods 8’6”’ to 9’6” take up the lion's share of today’s fly rod market. There is a lot of variety in these lengths due to the numerous designs that companies offer in these configurations. We see rods that are 9’ long in 3 weights all the way up to the heaviest fly rods that are made. Because of the versatility of this length, it isn’t worth discussing too many specifics, but know that this is the happy medium for many different fly fishing applications, as it strikes a balance with a number of different factors. 

This remote Idaho River held both Cutthroat and Bull trout. Alex Kolivras is seen carrying a second, heavier rod just in case an opportunity to throw huge streamers to Bull Trout presented itself.

Rods 10’ and longer have gone in two very different directions, and it is important to make some distinctions. Euro nymphing rods are extremely popular but have certainly strayed from what a long rod may have looked like traditionally. They are incredibly light for being so long, and they are designed around nymphing techniques that use very long leaders and sometimes eliminate the fly line altogether. These are specialty rods that are both popular and effective for what they are designed to do. Traditional 10’+ rods can offer a lot more versatility than Euro rods, and are more designed around casting fly lines. These are often used when fishing larger rivers where the added reach is an advantage for mending or holding line off of the water, or when fishing still water. In general, these rods are not as accurate and easy to cast as shorter rods, but can be an advantage in many scenarios. 

Shorter rods can be an advantage when fishing small streams in tight quarters. In these situations, typical 9 ft fly rods can be cumbersome. 


Something to keep in mind when sifting through this type of information is that your personal preferences, budget, and skillset may drive your decision making as much as any general information I can provide. When I first started fly fishing for trout, I used a 9 ft 6 Weight which was entirely overkill for almost all of the fishing I was doing, but it was the one rod I had. Despite this, I caught plenty of trout on tiny dry flies with that 9 ft 6 weight and never thought twice about it. Don’t be afraid to use the gear you have, or purchase a rod that can serve multiple purposes. As you invest more time into the sport, you will develop skills and preferences that will give you more clarity on which rods to add to your quiver. Sure, premium and specialty rods are amazing tools that you will surely appreciate when you get your hands on them, but many anglers can cover a lot of bases with just one or two rods. If you have the money to spend on multiple rods, you will see the benefits, but if you don’t, learning to use the one rod you do have will go quite a long way. As a starting point, choose a rod that suits the type of fishing you are most interested in or have access to, and add gear over time as you realize the limitations of what you already have. There is no one rod to rule them all, and trade offs are always part of the conversation. Because of this, I believe it's best to be aware of the basics, but not to overthink your gear especially as you’re getting started. 

An average Pennsylvania Wild Brown trout ate this massive streamer. You may not need a 7 or 8 weight to handle this fish, but you will need a heavy rod to cast flies like this. 

The chart below is a great starting point for choosing a rod for a specific purpose but isn’t the end all be all. It is worth noting again that these suggestions are vague, and you might find something that works for you that differs from what you see below. Also, nothing beats going into a fly shop and asking questions in person to somebody with experience.

As always, you can feel free to reach out to me with any questions about the article or if you have any specific questions about rods or tackle in general. Part two will focus on rod action, which will build off of the information above.

Thanks for reading!

Frank Landis

TCO Boiling Springs

Guide at Relentless Fly Fishing

IG: frankflyfishes

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Peter Zelov - March 14, 2023

Gives me a better understanding what a rod is built for and how to use the proper fly for that particular moment that you are looking for. Great article thanks.

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