What Breaking Strain Braid To Use When Trout Fishing?

What is the best diameter of braid to use on a spinning reel when trout fishing? there is so much conflicting information available online.

Should you match the diameter of the braid with the diameter of the monofilament leader?

In this article, I will answer these questions and more. But first, I will provide a concise answer, but will provide more details later.

The best breaking strain braid for trout fishing has a diameter of between 0.12 to 0.14mm (or 0.005” to 0.006”). This approximately means a rated breaking strain of between 2lb – 4lb. When targeting small trout, I use braid rated for 1lb-2lb, if the trout are of larger size, or if you are fishing in a highly abrasive waterway then consider going up to 4lb. I can not think of any situation where going as high as 10lb is required.

Firstly, most braid typically over tests

When buying a spool of braid, the ‘breaking strain’ on the retail box should be representative of the ‘breaking strain’ of the braid itself. Well, unfortunately, this is not really the case. Braid, and especially the braid marketed towards North American markets often over-tests by a significant margin.

I use to joke that 6lb Berkely fireline use to break closer to 6kg (13lb), Well, my joke was wrong. I have tested 6lb fireline quite a few times and it usually breaks around 18lb and occasionally over 20lb. I have also tested 1lb fireline crystal, it consistently broke at 5lb.

Based on my testing, 1lb or 2lb fireline is adequate for most trout fishing.

The other big names such as Daiwa J Braid, Sufix and Powerpro usually over-test in a similar fashion.

There are exceptions to this rule. Line marketed more for the Japanese market, (Toray, Siglon etc) is just as likely to under test.

Braid breaking strain is strongly correlated to diameter. The thicker the line, the stronger it is.

Below I will compare the rated breaking strains for Toray Superstrong (which breaks close to rating) and Berkely Fireline that greatly over tests.

Toray Superstrong (6.6lb / 0.128mm)

Berkely Fireline (6lb / 0.15mm)

As can be seen, the Fireline despite being marketed at only 6lb, is quite a bit thicker than the 6.6lb Toray. So to compare apples to apples, 4lb Fireline is comparable to 6lb fireline because the diameter is much more similar.

Advantages of a thin braid?

So, why fish a thin braid? Why not just match the braid diameter with the standard diameter of monofilament?

Braid has three main advantages over monofilament,

Sensitivity: Braid has less stretch, so is a lot more sensitive than monofilament. With regards to sensitivity, diameter does not really matter.

Memory: Braid, at least braid designed to be used on spinning reel has very little memory. I can not remember the last time I got a wind knot when fishing with fireline.

Casting distance: The final main advantage of fishing braid, is that it improves casting distance, but braid only casts further than monofilament if it has a lower diameter. If both the braid and monofilament has identical diameter then any advantage in casting distance is gone. I will even go as far to say that 0.20mm, or 4lb monofilament will cast further than 0.20mm or 10lb braid simply because monofilament is more sleek and less likely to cut into itself.

Other advantages of braid?

Above I listed what I consider to be the main advantages, but there are a few more.

Longer life: Braid typically has a longer storage life than monofilament that can easily be damaged by UV light.

Floats: Braid naturally floats, again diameter does not really matter, and floating is neither good or bad.

Sharpness: Braid due to its sharper design, often can slice through annoying weeds or stalks rather than getting snagged by them.

Disadvantages of using heavy braid?

Okay, there are some real downsides to using heavy braid, but the main one is that it is stronger than the ultralight rods and reels we trout fish with.

There are ways to limit the risk of damage, such as

– using an appropriate breaking strain leader,

– setting the drag to only a couple of pounds,

– or simply not brute forcing fish or breaking snags free.

But based on the number of ultralight rods and reels I have seen damage from someone trying to free a snag, it is quite apparent many fishermen do not respect the limits of their gear. An ultralight reel, such as a 1000 or 1500 series is really only engineered to handle 5 or 6lb of pressure at most so it is no surprise that something gives.

The problem is twice as bad when combined with the Chinese ultralight reels common on Amazon, these reels often come with an enormous drag. Much more than the reel itself can repeatability handle.

So, when fishing 4 or 6lb line, the line should snap well before anything more expensive, when fishing 20lb line all bets are off.

Why do some people suggest fishing 10, 20 or 30lb braid for trout?

I suspect the main reason some fishermen suggest using such heavy braid is because they are using braids that are not designed specifically for spinning reels.

Thicker braids are typically better behaved. They are less likely to cut into itself on the spool, or form loops during the casts which can turn into wind knots.

I do not want to say such braids are poor quality, they are not. They usually work fine on overhead or baitcasting reels. But they are simply not designed to be wrapped around tightly by the osculation of an ultralight spinning reel.

When trout fishing, just do not buy the cheapest braid, but buy braids that have been specifically designed for such a style of reel. My personal recommendations are Berkely Fireline, and the newer generations of Daiwa J braid. Sufix also handles well on spinning reels, but the lightest breaking strain is 6lb (0.14mm) meaning its true breaking strain is over 12lb.

If your knots keep failing, use more turns.

Due to the thin diameter, braid is a lot more slippery than monofilament. So typical fishing knots often do not hold. There are specialized braid knots, that break close to 100% line strength, but the easiest solution is usually just to use more turns in your normal knots.

I personally use the Aussie Quickie knot (Reverse Albright Knot) when trying lightweight braid to a monofilament leader. It is fast to tie and very solid (no need to tie a bimini twist first). When joining mono to mono it only requires 4 or so turns, but braid to mono I increase the number of turns to around 12 and it is rock solid.

I never tie braid directly to terminal tackle, and honestly, I do not recommend doing so when trout fishing. But, if you want to tie directly to terminal tackle. I suggest using a uni-knot but going through the eye twice and then doing about a dozen wraps around the mainline.


When trout fishing I like to use a braid with a diameter between 0.12 to 0.14mm (or 0.005” to 0.006”). The rated breaking strain, depending on brand is usually somewhere between 2 to 6lb, but keep in mind that such braids nearly always over-test.

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