Trouts Journal

Know Your Gear // Understanding Trout Hooks

Ivan Orsic / Sep 21, 2021

In this series Know Your Gear, I go in-depth about some of the details that are within the sport of fly fishing. From understanding, waterproof vs. water-resistant jackets or how to layer up for the upcoming fall months, this series is an opportunity for you as an angler to be more knowledgeable about the products you are purchasing or at the very least have some interesting bar talk. Today, we are covering the wide world of trout hooks. Although this topic alone has enough information to fill a book, I will try to keep it as concise and clear as possible. It is important to know that I will only be covering trout hooks in today's read. Saltwater hooks are an entirely different animal that I will take on at later date, but for now, sit back and enjoy this week Know Your Gear // Understanding Trout Hooks.

When you first step into a fly shop one of the many things you might overhear is, "What are they hitting on?". Naturally, the response you will receive is the name of the fly and the size of the fly, or vise versa. For example, if you came into the shop over the past couple of weeks and asked the question above we probably would have responded with something along the lines of "an Umpqua Hippie Stomper size 12". Sure you can just take this at face value and be on your way to catching trout but, what does a size 12 really mean? Let me explain.

When we look at fly sizes and trout hook sizes the numbers are inversely related to the size of the hook or fly. This means that as your number increases further away from 0 your fly or hook will be getting smaller in size. It is a touch confusing, isn't it? Just wait there is more. Typically, if you are visiting a U.S. fly shop the most common numbers you will see when shopping around for flies are the numbers 12, 14, and 16. Why? Well, that is because in general those three sizes are typically the size bugs trout actually eat when it comes to dry flies, wet flies, and nymphs. When we look over at hoppers, i.e. grasshoppers, Chubby Chernobyls, and other large hopper style bugs, those typically are found in hook sizes, 6, 8, and 10. And, just like the flies mentioned previously the sizes 6, 8, and 10 are the most common size you will find these bugs out in the wild. However, don't think you should be only using these sizes all the time, typically here in Colorado or other high pressured water systems you are better off using sizes 18, 20, or 22. Another interesting thing about flies and hooks? Here in the U.S., flies, and hooks only come in even numbers. If you were to venture over to Europe that is where you will find odd numbers used when determining fly size. Don't believe me? Come take a look for yourself!

How Hooks Are Defined

Now that we have gotten some of the simpler things out of the way it is time to dive into the hard stuff. More specifically, how hooks are defined. When we look at hooks and hook models we will see that they are defined by two sets of parameters: the diameter of the wire used in making the hook and the length of the hook shank (image above for reference). Most of the time, when you are tying up flies or purchasing them they will be tied on standard-sized hooks and wire. As an example, Dry Flies are tied on a light-wire hook (for increased buoyancy), Nymphs on a heavy wire hook (for increased sinking ability), and Wet Flies on a standard wire (for light sinking). This can be distilled down to the simple idea of a bigger wire equals a heavier fly, and a lighter wire equals a lighter fly. If you were thinking, "Brandon what about streamers!" those my friend would typically be tied on a heavy or standard wire with an extra-long hook. It is kinda like a math problem honestly, If you want (x) then you must use (y).

Now, stay with me here because this might get a bit confusing. If you find yourself venturing away from standard hook sizes and wire you will find yourself dealing with the letter X. It is important to remember that the letter X is referencing your standard hook size and wire. So, any deviation you make from X will be one standard hook size and wire away from your X. Like I said, stay with me here.

When you find yourself dealing with the letter X you will typically be finding the terms 1X, 2X and 3X used, and within these categories, you get different variations. Remember that the letter X means your standard hook size and wire. Within these variations, you will see the terms fine, heavy short, long, and extra-long used as well. The terms Long and Short are a reference for the length of the hook compared to the standard(X), while the terms Fine and Heavy reference the wire used compared to the standard (X). Let's break it down even more.

If you were to come across a fly or package of hooks that were denoted as 1X Long you would be dealing with a hook that has a shank length that is one (1) size larger than X (your standard hook size). If you find yourself looking at a fly or package that is denoted as 2X Long you would be dealing with a hook that has a shank length that is two (2) sizes larger than X (your standard hook size). When you see the term 1X Fine you will be dealing with a hook that has been made with a standard wire (X) for one (1) size smaller. If you see 2X Heavy that means you are dealing with a hook that has wire made for a hook two sizes larger. Is this making sense yet? Hopefully, it is. Let's dive into the fly categories and see where we find each term used. That may make it a bit more clear.


When we look at dry flies one of the most common hook models used is a TMC 900BL (Barbless), TMC 100BL, and TMC 2302. Typically these will be standard in length (remember X) and be denoted as 1X Fine. So, that means that these flies will be tied on a hook that has a standard hook length but the wire will be one for one hook smaller. This increases the ability to present the fly delicately on the water and will allow the fly to float better on top of the water. The most common fly sizes you will see will range from size 10-20.

Nymphs and Wet Flies

When we look at Nymphs and Wet flies, we will notice that we can typically tie these on the same style of hook with a bit of variation. When we look at Nymphs we will typically be seeing a hook that is 1X Long, 2X Long, 1X Heavy, and 2X Heavy. Why so many? Because when nymphs are tied they need to imitate a larger variety of bug life than a dry fly or streamer. The most common models you will find are the TMC 3761 are TMC 3769. However, when you start looking at larger stonefly imitations they will be tied on a curved style hook with will come in a 3X Long or 2X Heavy, a good example of this would be a TMC 5262. If you are tying up more scuds or caddis pupas you will find that these are best tied on a 1X or 2X Heavy due to the ability to sink better than a standard or fine. If you decide to tie up some wet flies or pick them up from the shop you will notice that these are also tied on 1X or 2X Heavy hooks. The most common models are the TMC 9394 and TMC 3769.


Whenever you see someone tossing a large streamer towards the banks, chances are that the hook they are tied on is relatively large. Most of the time you will see these bad boys tied on 3X or 4X hooks with heavy wire. The most common models are going to be the TMC 5263, TMC 9395, and Montana Fly Companies MFC vertical or horizontal hooks.

conclusion and final thoughts

Holy cow, that was a lot. I know. Trust me, it is a lot to take in at the start, and honestly, the best way to learn this stuff is to read and re-read. However, once you understand hooks and why certain styles are used you will elevate yourself from the rest of your angling friends. You will be able to make more informed decisions when you are out on the water and feel confident in what you are doing. As I wrote this post I found myself learning more than I did originally when I had the idea to write about this. More importantly, I found myself being able to articulate the ideas mentioned today better. If you are still struggling with the topics covered in today's post, send me an email with any questions you may have. Or, come swing by the shop. We are here to help you maximize your time on the water and understanding the world of trout hooks is a great starting point.

Shopping Cart


Free shipping over $50.00

Shipping & taxes calculated at checkout

Checkout View / Edit Cart


Sold Out