What Pound Test Leader For Trout

An angler that knows what pound test leader for trout is the best.

I guide many clients to big brown trout like the one my client is holding in the picture above. I know that it’s very important to know what pound test leader for trout is best to use so that you not only get more bites, and so that you don’t have many break-offs. What pound test leader for trout is a common question that anglers want to know.

The best pound test leader for trout for slow presentations and with bait or flies is a 4-pound leader which is around 0.14mm in thickness, and for lure fishing you want to use an 10-pound leader which is 0.22mm in diameter.

It’s best to purchase your leaders based on the diameter of the leader and not based on the pound test listed on the spool. It’s also best to use a fluorocarbon leader and not mono.

There are times when the leader for trout will need to be bigger and times when I might go lighter. I will discuss this and more below.

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What Pound Test Leader For Trout?

There are two primary things I consider when determining the proper pound test leader for trout. A trout leader should be:

  • Strong enough to not break off
  • Thin enough to not be seen by the trout

The problem is that not all leader brands rate their leader labels accurately and this could mean fewer fish. Therefore you need to make sure that you purchase the right size of leader.

I will explain more below how to do this, but since brands don’t rate their leader properly, I can’t just say use a 4-pound leader, because depending in the brand, 4-pound leader might not be the right pound test leader for trout.

And yes, based on my experience, it matters a lot, because a leader that is too thick can result in fewer bites.

I’ve seen this happen firsthand. I’ve had clients that have fished and struggled for years on their own and I like to try to figure out why, what are they doing wrong.

In many cases, they will tell me they use 6-pound leader because that is what they were told to use. Six-pound test seems very reasonable for trout until I ask them what brand of leader they are using or ask them to see the spool of leader. Many times, even though their leader says 6 pounds the leader is as thick as a 10 or 12-pound test leader, and that is too thick and prevents them from getting bites.

Once I switch them to the right size leader they catch a lot more trout.

A leader that is too thick won’t get any bites because the fish see it, especially in clear water or in slow water where the trout have time to inspect the bait. I have proven this many times.

However, a leader that is too thin will break too easily and you will lose too many trout.

I often say that the pound test leader that is best for trout when using bait in clear water is 4 pounds with a line diameter around 0.14mm, because it’s not too heavy and it’s not too light. The line diameter is the key.

But under certain conditions, you might hook more trout with a thinner leader or you might need a thicker leader to land more trout.

The river conditions and the method you use will dictate what pound trout leader you should be using.

Under different conditions and using different methods, you will need to change your leader size.

I would use a very different size leader when float fishing than I would when casting lures or when streamer fishing. I will also use a different leader size in a river that is 15 feet wide than I would in a fast-flowing river that is 200 feet wide.

I will discuss what the best leader is for each.

Leader Sizing Important – My Warning

Leaders for trout

This is very important to know and is something most anglers don’t know.

Using the right size of leader has many advantages, but not all leaders are labeled properly, or should I say labeled accurately, and this could mean fewer fish if you are unknowingly using the wrong sized leader.

I have seen anglers struggle to catch trout for years simply because they didn’t realize that the leader they were using was mislabeled. Once they figured out the leader was the issue they were able to catch trout.

I have seen leaders labeled as 4-pound test, but they were closer to a true 6 pound or even an 8-pound breaking strength which is too heavy for trout.

One brands 4-pound leader might be exactly 4 pounds and will be perfect for trout, but another brands 4-pound leader might be as thick as 8-pound line and that is bad for trout.

This is why I always tell my clients that it’s always better to buy your trout leaders by the diameter size and not by the pound test on the label. It’s very important to remember this.

Most of the time the diameter size is a more accurate reflection of the true breaking strength of a brands leader. And even if it’s not, when it comes to leader size and actually getting trout to bite, what really matters is the thickness of the line and not the pound test of the line.

The reason is that a thick line will be seen and ignored by the trout, but a thin line will not be detected and you will have more trout bite. The key to leaders is you want a leader line for trout that is strong enough that you won’t be breaking off any fish but thin enough that they will bite your bait in the first place.

That is where a true 4-pound test (0.14mm thickness) is what you want for bait fishing and slow presentations and for lure fishing a true 6-pound ( 0.16mm) or a true 8-pound test (around 0.20mm diameter) leader is best.

Leader mislabelling is very common.

As an example, if you compare 4-pound Drennan leader, 6-pound Seaguar leader, and 8-pound Rio leader, you will see that they are all the same 0.20mm/ 0.007″ diameter.

All three leaders are the same diameter and therefore they would all likely break at approximately 7 to 8 pounds if you actually tested them. But they all have different pound ratings on their label which usually means two of the three are actually mislabeled.

I have had guys walk into my tackle store to return line for this very reason. They buy one 4 pound leader that is super strong and then they try another brands 4 pound leader and it breaks. They think the leader that breaks is just a crappy line but what they don’t realize is that the super-strong 4 pound is actually 8-pound test and the other lines is true 4 pound.

So when someone tells you that for trout you should use a 6-pound leader, 6 pound Rio brand might be what they are talking about and not 6-pound Drennan which is as thick as most brands 12-pound line. Ask them what diameter it is instead.

This chart is based on actual tests and is a more accurate way to buy your leaders.

Pound Test



.003in (.08mm)


.004in (.10mm)


.005in (.12mm)


.0055in (.13mm)


.007in (.18mm)


.008in (.20mm)


.009in (.22mm)


.010in (.25mm)

For heavier leaders of 6 pounds to 12 pounds when fishing lures, I like to use Seaguar or Drennan leaders but remember to only go by the diameter and not by the label pound rating because Drennan 3 pound is actually closer to 6 pounds, and 4 pound Drennan is actually closer to 8 pound, while 5 pound is about 10 pounds and 6 pound is about 12 pounds.

For lighter leader lines in small spools, I like to use Rio FluoroFlex + Tippet. Check the prices at Trident Fly Fishing  FishUSA.com, or at Amazon at these links.

Don’t forget to check out our newest page Trout Fishing 101: Learn Guide Tips And Tactics For More Trout where I share tips and advice from guides so you can learn how to fish for trout better.

The Downside To A Heavy Leader For Trout

The main disadvantage to a trout leader that is too heavy is that the leader might be seen by line-shy trout. This might mean fewer fish will bite your bait. This matters more when fishing certain baits and in certain water conditions like when the water is super clear or slow moving.

The advantage to using a bigger leader for trout is that you won’t break off as many fish and I might upsize in faster water or in a river with a lot of wood and snags. I always prefer to use a lighter leader because I think having more bites and losing a few fish is better than getting no bites at all.

The Rod Makes A Difference

Before you read any further and before you hear my advice and recommendation on leader sizes for different situations, you should know that I tend to use longer and lighter rods whenever possible.

Longer lighter rods allow me to use lighter leaders because the longer rod acts like a big shock absorber that protects the leader from breaking.

Using shorter stiffer rods might require you to be more careful and lighten up on your drag a little so you do not break off. Lighter leaders tend to break more often on short stiff rods.

I discuss rods on my page Best River Fishing Rods: Trout And Steelhead Rods

The Advantages Of Using A Lighter Leader For Trout

Big trout like this are caught on light leaders
Big trout are wiser and more line shy. The lighter your leader the more big and small trout you will catch.

There are some real advantages to a lighter trout leader and some advantages you probably do not know about. I always use the lightest leader possible and many of the tournament pro anglers use leaders as light as two pounds.

  • A lighter trout leader won’t be seen by line-shy fish.
  • A lighter trout leader will sink faster
  • A lighter trout leader won’t get pushed around by the current and your bait won’t move abnormally fast
  • A lighter trout leader might allow your bait to move and drift more naturally in the current.

The thicker the line the more surface area there is and that can mean that a thicker line will get pushed by the current more and that will increase the speed of your bait which can result in fewer bites.

I always go with as light a leader as I can get away with for the size of the fish and the type of water that I am fishing.

What Pound Test Leader For Trout Is Best In Clear Water?

An angler fishing in clear water
This angler is fishing a clear fast water trout river with a 3 pound leader line. The light leader will get his fly down fast and help it move slower.

In ultra-clear rivers like you might find on some spring creeks that a 3 pound (0.12mm) or 4-pound (0.14mm) leader is a good choice for trout when you are float fishing or using the bottom bouncing method.

I also use this size when fly fishing for trout.

Why 3 pounds? If the trout are being line shy I will use 3-pound test leaders so they do not see it. 3 pound is .005″ or 0.12mm diameter. This lighter leader also allows my bait to sink faster and move more naturally in the current.

Therefore, the best pound test leader for trout in clear water will be a three pound leader.

What Pound Test Leader For Trout Is Best In Dirty Water Water?

An angler fishing in dirty water for trout

In dirty water, you can go up a size or two because the trout can’t see the line, and using a slightly heavier line will allow you to get the trout in the net faster.

Dirty water makes it harder to see rocks and snags and a heavier line won’t scratch or break as easily when you hit these obstructions.

Therefore, the best pound test leader for trout in dirty water will be a 6-pound leader.

What Pound Test Leader For Trout Is Best In Slow Water?

I treat slow water the same way I treat very clear water because in slower water the trout have more time to inspect the bait and they are more likely to see the line and refuse your bait.

Therefore, the best pound test leader for trout in slow water will be a 3-pound leader. 3 pound is .005″ or .12mm diameter

What Pound Test Leader For Trout Is Best In Fast Water?

4 pound leader are good for trout in faster water

When the water is faster the trout have less time to react to a bait moving at them and they have less time to see the line. Therefore, in faster water, a 4-pound leader should be fine for trout. The 4-pound line is .0055in or 0.13mm to 0.14mm in diameter.

With that being said, I still use a 3-pound line more often even in faster water simply because the 3-pound line won’t get pushed as fast by the current which allows my bait to travel slower and this often results in more bites.

Therefore, the best pound test leader for trout in fast water will be a three or four-pound leader.

What Pound Test Leader For Trout Is Best In When Euro Nymphing?

Many professional tournament anglers that use the Euro nymphing methods will use very light leaders for trout.

They do this because it allows their flies to sink faster which gets the flies in the strike zone faster and the thinner leader slows the flies down. It’s not uncommon for tournament pro anglers to use 1.5 to 2-pound leaders for trout. 2-pound line is about 0.10mm

I only recommend going this light for anglers that are really good and that use longer rods.

For most of my Euro nymphing fishing and guiding, I use 3-pound leaders but I will upsize to a 4 or 5-pound leader in heavily wooded water, or if there are a lot of big fish over 5 pounds.

Therefore, the best pound test leader for trout when euro nymphing will be a three-pound leader.

What Pound Test Leader For Trout Is Best When Indicator Fishing?

Indicator nymphing

For indicator fishing for trout, a 4-pound 0.13mm to 0.14mm leader will work in most river situations.

I use 4 pounds if I want to put split shots on the line because the split shots are less likely the damage a thicker line.

If I want to get my fly deeper faster I will drop down to 3-pound leaders for trout.

For information on how to indicator fish better check out my page Indicator Nymphing: 13 Tips From An Expert River Guide.

Therefore, the best pound test leader for trout when indicator fishing will be a three-pound leader.

What Pound Test Leader For Trout Is Best For Dry Fly Fishing?

Best pound test leader for dry fly fishing

Leaders on the surface can create an indent in the surface that trout can see. That is why most dry fly fishing usually requires a thinner line so the line-shy trout do not see the line.

I also use mostly monofilament leaders when dry fly fishing because they are light and they float. Fluorocarbon line is not great for dry fly fishing since it sinks and that could pull your floating fly under.

Therefore, the best pound test leader for trout when dry fly fishing will be a two to 3-pound leader.

What Pound Test Leader For Trout Is Best For Streamer Fishing?

dry fly fishing leader

When using streamer flies for trout I will use 10 to 12-pound leaders (0.22mm to 0.24mm).

Because the fly is moving faster the trout will be focused on the fly and are less likely going to see the leader.

The other reason I use a 10-pound test leader for streamer fishing is that streamer fishing often gets the bigger fish to bite and when they hit the fly they hit it hard and fast.

A hard-hitting trout can break a 6 or 8-pound leader on contact sometimes so I rarely use less than 10 pounds when streamer fishing.

Therefore, the best pound test leader for trout when streamer fishing will be an eight-pound leader.

What Pound Test Leader For Trout Is Best For Swinging Wet Flies?

When swinging wet flies for trout the line is mostly tight and the fly is moving and there is less of a chance that the trout will see the leader.

Because the fly is moving and the leader will be tight, a bigger stronger leader is required so the fish don’t break you off on the bite.

I use 6-pound 0.18mm leaders when fishing with wet flies.

Therefore, the best pound test leader for trout when swinging flies will be a four-pound leader.

What Pound Leader Is Best For Lures?

Fish Flies With Spinning Gear

Sometimes when you are lure fishing you might be using a braided line or a colored line and you may need to add a piece of leader so that the trout don’t see it.

Because the lure is moving the trout can hit the lure hard and fast therefore you will need a leader of 6 to 8 pounds. 0.18mm to 0.20mm

Most of the time I will use a true 6-pound 0.18mm leader for trout when casting lures but I will up-size to a 10-pound .009in (.22mm) leader for steelhead and even up to 12 -14 pound for great lakes salmon.

Therefore, the best pound test leader for trout when lure fishing will be an eight-pound leader.

Got a question about what pound test leader for trout is best, let me know in the comments below.

I hope you enjoyed my post about What Pound Test Leader For Trout and that it helps you catch more trout.

Tight lines


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  1. Hi Graham,
    Thanks for all of the info you are sharing on the site. Amazing stuff!

    I like to use an ultralight rod and reel for medium and small creeks.

    If I am using spinners or micro jigs, is it ok to just go direct from mainline without a leader? I use p-line floroclear 4lb. (.18mm)

    I recently downsized to 2lb floro and got burnt on a large trout that easily snapped the line, so I plan to go back to 4lb.


    1. Hey Matt, When using lures that move quickly the trout are less likely to see the line so with lures I will often upsize my line to 4 or 6 pound test so I don’t lose fish, and it is OK to tie a your 4lb Floroclear line directly to the lure without a leader.

      With slower moving baits and maybe with your micro jigs, depending on how you use them, I would tie on a 2 foot floro leader using a triple surgeons knot or a swivel or tippet ring. I use a leader because fish have more time to inspect the slow moving bait and then maybe see the line. Also, tying floro to mono just hasn’t worked well for me so I use a micro swivel for that type of connection.

      Remember that your 4 pound mainline is 0.18mm and most 4 pound leader brands like Rio Fluoroflex 4.5lb is much lighter at only 0.14mm, and 2 pound leader is only 0.10mm, (depending on the brand), which is really, really thin line and is even too light for me in a lot of cases so I’m not surprised it broke on a big fish.

      If you want to try a slightly lighter leader for bait fishing I would suggest dropping down to 0.16mm, or 0.14mm. (stop using the pound test rating on the spool and stick with the diameter instead) I have caught hundreds of 18 to 26 inch brown trout on 0.14mm line, however I’m also using 9 and 10 foot rods.

      I’m in the middle of writing an article about catching trout in small streams and I discuss the idea of using longer rods so that you have more leader protection and more control on your presentation when bait fishing. I know this will sound odd to many guys that like their 5 and 6 foot rods for small stream trout, but the trend in fly fishing with the pro tournament anglers is to fish with 10 foot rods, even in small streams. There are many advantages to longer rods including light-leader protection which is why the pro’s use them.

      There is no reason why you wouldn’t have the same benefits with a 8, 9 or 10 foot ultra-light spinning rod. However, if you’re primary means of fishing is casting lures a shorter rod in the 7 foot range may still be a better option. The new page should be published on May 7th 2021

      1. Thanks for the reply Graham.
        Lots of great information!

        I do have an 8 1/2ft St. Croix. I will try switching over to that!

        The idea of a longer rod to support the lighter line makes perfect sense. Much like longer rods for steelhead.


    2. Hi Matthew,

      I live in Rawlins, WY and spend a lot of time fishing on the North Platte River. Question: on a spinning reel with braided main line and fluorocarbon leader should I use a snap swivel with spinner lures or just tie the line directly to the lure? Is so, what know do you recommend?

      Joseph Stewart