What is Fly Rod Weight and How to Use Our Fly Rod Weight Chart

If you're wondering what fly rod weights are and why they matter,  keep reading.

It's easy to understand why people get confused about fly rod weights. After all, there are line weights, reel weights, rod weights, and fly sizes.

When I take beginners fly fishing, I always get asked to explain fly rod weight.

You don't need a college degree in fly rod engineering to get fly rod weights right.

But you do need a basic understanding of how these fly weights and sizes work together though so you can select the right fly fishing setup for yourself.

Here I'm going to share some history of fly rod weights and how to choose the best fly rod weight for your fly fishing situation.

 Fly Rod Weights

Article Outline

What is fly rod weight?
How is fly rod weight used?
How are Fly Rod Weights Measured?
1. In Theory
2. In Practice
What does overlining your fly rod mean?
Why overline your fly rod weight?
What does underlining your fly rod mean?
Why underline your fly rod weight?
The Challenge of Overlining or Underlining Your Fly Rod Weight
How to Overline Your Fly Rod
How to Choose the Best Fly Rod Weight
Fly Rod Weight Chart
The Best Fly Rods for Specific Species
The Best Fly Rod Weight for Trout
The Best Fly Rod Weight for Bass
The Best Fly Rod Weight for Salmon



Before I start, I want you to know these are some very broad generalizations.

The choice of fly rod length and weight varies by species and location very specifically.

So while I've tried to provide some guidance for you, I want you to think of these suggestions as starting points or anchors from which you can upsize or downsize your choice of fly rod to meet your fishing needs.

What is Fly Rod Weight?

Fly Rod weight refers to the strength of the fly rod. The higher the fly rod weight, the stronger the fly rod.

Fly Rod weights range from 1 to 15 but typical fly shops will carry fly rod weights between 3 and up to 11, if you are shopping in a fly shop near big waters.

The higher the fly rod weight, the larger the fish and bigger water you're fishing, the longer the rod and heavier fly rod weight you'll need. 

How is Fly Rod Weight Used?

In fly fishing, fly rod weights are used to match a fly line, a fly reel, and a fly rod to the species and fishing environment.

As a rule of thumb, weights are supposed to match the line to the reel to the rod.

For example, a 5-weight rod should have a 5-weight reel loaded with a 5-weight fly line. 

How are Fly Rod Weights Measured?

Fly Rod Weights In Theory

Fly rod weights merely reference fly line weight.

So the real question is 'How are fly line weights measured?'.

Fly line weights are measured in grains, a unit of weight measurement dating back to medieval times and wheat grains.

I'll skip the history lesson but just for perspective, 1 grain is 0.065 grams so 1 gram is 15.38 grains.

After World War II, production of fly rods increased and fly line manufacturing was not uniform. Consumers found it difficult to match line with rod and reel.

In 1959, AFFTA (the American Fly Fishing Trade Association), published fly line weight standards.

The goal was to have a 5-weight line of one manufacturer match another manufacturers rod or reel.

Today, AFFTA still publishes the Standard Line Weights to maintained standards for fly line grain weights. Here's the most recent version of those standards.

Fly Rod Weights AFFTA

In their own words, AFFTA creates and maintains industry standards to help manufacturers comply with tolerances, and to help retailers provide customers with well-matched equipment and components.

The weights of the various fly lines (1-15) are provided both in grains and grams. The weight is the measurement of the first 30' of a fly line.

The idea here originally was that the average fly rod cast was 30'. So AFFTA used 30 feet beyond the tip of the rod to measure how much line weighed.

Then manufacturers produce fly rods and reels in weights that cast best with those weight of lines.

Fly Rod Weights In Practice

In short, there’s no standard measure of power in fly rod manufacturing.

So a 5-weight fly rod by one manufacturer will not produce the same cast as another manufacturer’s 5-weight fly rod.

Over time, fly rod manufacturer’s have developed proprietary methods of determining what weight a fly rod is.

But the average fly fisher has changed. For decades fly fishing rods have been getting stiffer and more powerful.

Fly fishers want to cast further and easier. To do this, manufacturers have slowly evolved how they make rods.

The challenge is that fly rod manufacturers all have different methods of determining what weight a fly rod is.

So while there is an industry standard that is followed for fly line, fly rods and reels are not standard.

This is important to remember when choosing a fly rod weight.

This doesn’t mean you should ignore matching a line with a rod and reel. But it does mean you should never blindly accept the weight matching principle.

When choosing a fly rod, reel, and line, matching their weights is a starting point.

If, however, you don’t like how the fly rod weight setup feels, don’t hesitate to try different weights. This is called overlining or underlining your fly rod.

What does overlining your fly rod mean?

Overlining a fly rod is when you use a heavier weight line than your rod weight.

For example, if you put a 6-weight line on a 5-weight rod, you’re overlining the fly rod.

I’ve never seen any reason to overline a rod one or at very most two weights above your fly rod.

If you have to because that’s all you have, it may work. But as a standard of practice, overlining is generally discussed in terms of one fly line weight above your fly rod weight.

Why overline your fly rod weight?

Remember that in fly fishing, as opposed to spinner fishing, the weight of the line and NOT the fly or lure carries the cast forward.

But what if your fly rod feels heavy relative to your line? What if you can’t feel the fly rod load your line or you’re unable to get very accurate with your cast because your fly line seems too light?

Overlining is a great way to help solve three casting challenges.

First, if you’re fishing a stiff, fast rod, you may not be able to feel your line loading. For beginners, it’s important that you can feel that load to time the cast properly and deliver the full length of your line to your target.

Second, if you’re fishing in a situation that calls for a shorter line or leader length, a heavier line will help carry your fly forward.

Lastly, wind can make it difficult to cast. If you’re using a lighter weight rod, like a 5-weight or less, your casting might benefit from a heavier line that can better punch through windy conditions.

What does underlining your fly rod mean?

Underlining a fly rod is just the opposite of overlining. Underlining a fly rod means you use a lighter weight line than your rod weight.

For example, if you put a 4-weight line on a 5-weight rod, you’re underlining the fly rod.

Why underline your fly rod weight?

There aren’t many practical applications of underlining a fly rod for the beginner and even intermediate angler.

But in specific advanced situations, underlining a fly rod can give you the ability to cast at shorter distances more accurately if you’re using a slow rod (i.e. a fly rod that doesn’t flex or bend as much relative to other fly rods).

Casting with an underlined rod setup can take some practice.

If you’re interested in seeing how underlining your fly rod impacts your casting, do this at home in your backyard before you try it out on the water.

The Challenge of Overlining or Underlining Your Fly Rod Weight

While fly lines are standardized, the standards still provide enough wiggle room to make overlining or underlining tricky. Here's why (fair warning: this is a gravity-sucking black rabbit hole of detailed information):

The AFFTA chart dictates that a freshwater 5-weight line should be between 134 and 146 grains (or 8.7 to 9.4 grams).

If we look at a popular fly line 5-weight, we can see where in this range the actual weight falls.

Scientific Anglers 5-weight Amplitude Trout, for example, weighs 140 grains in it's first 30 feet. That's right in the middle of AFFTA's 134-146 5-weight range.

Fly Rod Weight - Overlining Amplitude Trout

Scientific Anglers 5-weight Amplitude Infinity, on the other hand, weighs 150 grains in it's first 30 feet. That's 4 grains over the maximum AFFTA standard of 146 grains for a 5-weight line.

Fly Rod Weight

Here's the challenge with the fly line weight standards.

1. The overweight choice pre-overlines a weight-matching rod.

If you buy a 5-weight rod and reel and then setup the Amplitude Infinity 5-weight at 150 grains on your rod, you're already overlining because your fly line weight is between a 5-weight ceiling of 146 grains and a 6-weight line floor of 152 grains per AFFTA's standards.

2. If you choose to overline your weight-matching rod, you're now overlining your rod by more than you think.

If you buy a 5-weight rod and reel and then setup the Amplitude Infinity 6-weight in an attempt to overline your rod, you've now overlined your rod to nearly a 7-weight line at 175 grains with a minimum of 177 grains per the AFFTA standard. This can cause casting problems like slapping a flies landing, for example.

3. If you choose to underline your 5 weight-matching rod, you're now only matching the rod weight.

Per AFFTA, the maximum weight for a 4-weight is 126 grains and the minimum weight for a 5-weight is 134 grains. But the Amplitude Infinity 4-weight stands at 130 grains, between the standard for a 4-weight and a 5-weight.

Before I go bagging on Scientific Anglers, I want to point out two things.

First, I love Scientific Angler's products.

Second, and more importantly, the company is overweighting their line for good reason.

Fly rods are being manufactured increasingly fast. Fast rods tend to cast better with heavier line.

So Scientific Angler is trying to help you cast better by selling you the heaviest possible line they can barely within industry standards.

I also want to note that other Scientific Angler fly lines, like their Amplitude Trout line, are spot on AFFTA standards.

Scientific Angler is just one of many fly line manufacturer's that practice this overweighting with some regularity.

The key idea here is that before you go overlining or underlining your fly rod weight, do a little research about the fly line you're buying and whether or not you'll be setting up with your intented weight.

The AFFTA fly line weight standards don't compensate for your inherently fast or slow fly rod.

How to Overline Your Fly Rod

1. Start with your rod and reel weight.

2. Understand what the grain weight of your fly line is that you have presently setup.

3. Research the fly line weight you're thinking of buying for your rod and understand where it falls in relation to the grain weight of your existing fly line.

4. If the change from your current fly line weight to the next fly line of your choice will truly increase the weight by 1x, then proceed with the purchase.

5. If the change from your current fly line weight to the next fly line of your choice won't increase the weight by 1x or increases the grain weight of your fly line by more than 1x, just be aware that this may cause your casting issues.

To be fair, 2x'ing the weight may not cause you any issues but if you're having casting problems after putting on a new heavier line, your fly line weight would be a good starting point to figure out your problem.

How to Choose the Best Fly Rod Weight

The myriad of choices from general purpose fly rods to euro-nymphing specialty rods knows no bounds.

If there’s a market for it, chances are one of the fly rod manufacturers makes it.

Maybe you prefer and can afford to buy a wide variety of fly rods for very specific fly-fishing situations.

Or maybe you’re looking for one general all-purpose rod that can cover 80% of the situations you’ll find yourself fishing.

Either way I’ve got you covered.

Fly Rod Weight Chart

I’ve put together the Fly Rod Weight Chart below.

If you know what fish you’re fishing for and you know where you’ll be fishing, this fly rod weight chart is for you.

Here’s how to use it.

1. Find your target fish in the first column. For example, let’s say trout.

2. Now find your fishing environment in the first row. For example, let’s a say a medium sized river.

Answer: Your starting point for a fly rod is a 9’ 5-weight rod.

Note I use the word starting point. The information in the chart is just that, a starting point. You should be just fine using a rod close to the chart’s recommended starting point.

Lakes and Ponds Small Stream Medium Rivers Large Rivers Beaches Saltwater Flats Offshore
Fish Species Trout 8' 4-Wt. 7' 3-Wt. 9' 5-Wt. 9' 6-Wt.
Panfish  8' 4-Wt. 9' 5-Wt. 9' 5-Wt.
Bass 9' 6-Wt. 9' 5-Wt. 9' 5-Wt. 9' 7-Wt.
Steelhead 11' 7-Wt. 11' 7-Wt. 13' 8-Wt.
Bonefish 9' 9-Wt. 9' 8-Wt.
Salmon 10' 8-Wt. 13' 9-Wt.
Saltwater  9' 9-Wt.
Big Game  9' 14-Wt.

But there are a variety of situations that could call for different rods than the above chart states or you may already have a fly rod that's 'close enough'.

Here are the tolerances from the chart I recommend:

  1. 6 inches longer or shorter than the rod mentioned (8’ 6” or 9’ 6” in the example given).
  2. 1 weight heavier or lighter (4 weight or 6 weights in the example given).

If you already have a rod within these tolerances, there is absolutely no need to buy a new or additional fly rod simply because yours doesn’t exactly fit the chart.

Using a rod outside of these tolerances may still fish just fine.

It simply means that if you had your druthers, I’d recommend using the chart to pick your sized rod.

The Best Fly Rods for Specific Species

I don’t like to generalize when it comes to helping someone select a fly rod.

Someone fishing for trout in a small pond in the northeast is going to need a very different rod than someone fishing a big river out west, even though both may be fishing the same species.

But to keep you happy, I’ll give you some starting points.

What’s the Best Fly Rod Weight for Trout?

A 9’ 5-weight fly rod is the best fly rod to catch trout. However, you should know that this can vary by the type of trout and the location where you’re going to be fishing.

For example, if you’re fishing a medium-sized river thats fairly wide open from a drift boat, the 9’ 5-weight will serve your needs just fine.

If, on the other hand, you’re fishing a small mountain stream for small brook trout, you can easily shift down into an 8’ 6" 4-weight.

Or, if you’re fishing a large river in windy conditions for larger trout, you might want a 9’ 6” 6-weight or even a 7-weight rod to really punch those casts long distances.

But for most conditions, a 9’ 5-weight fly rod will be the best fly rod for trout.

What’s the Best Fly Rod Weight for Bass?

A 9’ 6-weight fly rod is the best fly rod to catch bass. Again, this can vary by location.

For lakes and ponds, I prefer to use a 6-weight and in very large lakes known for trophy bass, even up to a 7-weight.

For rivers and streams, I prefer to keep the weight down to a 5-weight.

This is always open to personal preference, but these are just some starting points.

What's the Best Fly Rod Weight for Salmon?

A 10’ 8-weight is the best fly rod to catch salmon.Salmon can vary dramatically in size though from 20 lbs. up to 80 lbs. monsters.

So generalizing across the five most common species of Salmon with one rod is not easy.

Depending on your location, don’t be surprised if a guide hands you a 13’ 10-weight spey rod.

If you’re going Salmon fishing, talk to someone that’s fished the waters you’re targeting or chat with a guide local in that area.

The range of applicable rods to catch salmon on the fly could justify an entire blog post in and of itself. 

More Reading

If you simply can't get enough fly rod weight talk, here's a few more articles:


I’ll sum this article up for you and hit the main points:

  1. Fly rod weight refers to the strength of a fly rod. The higher the weight, the stronger the rod.
  2. Fly line weights are mostly standardized across manufacturers.
  3. Fly rod and fly reels weights are NOT standardized across manufacturers.
  4. Overlining a fly rod means using a heavier line than the fly rod calls for.
  5. Underlining a fly rod means using a lighter line than the fly rod calls for.
  6. Generally speaking:
    1. A 9’ 5-weight fly rod is best for trout.
    2. A 9’ 6-weight fly rod is best for bass.
    3. A 10’ 8-weight fly rod is best for salmon.

If you have any questions or want a personal recommendation for a fly rod, always feel free to reach out to us at and we can offer some advice.

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