Fishing Line Diameter Chart: Braid, Mono & Fluoro Compared


We’ve taken the guesswork out of knowing what diameter you can expect your line to be for a given breaking strain in monofilament, fluorocarbon and braid.

Once you know the diameter of the fishing line you have chosen to spool your reel with, you can then work out how much line it is likely to hold.

Knowing fishing line diameters is also useful for thinking about how lures might behave, how resilient your line is in rocks and heavy structure and how much wind resistance you will get on a cast.

Fishing Line Diameter Chart: Tabulated and Compared

Our friends at the Wildlife Department of Oklahoma produced this great table below showing the relative diameters of these three line types for a bunch of typical breaking strains.

Line TestMonofilament diameterFluorocarbon diameterBraided line diameter

Braided line: diameter chart

As you can see in the fishing line diameter chart here, braided line tends to be between 35 and 45% lower in diamenter then either mono or fluoro line.

For example, at 6lb test, mono and fluoro line in the Oklahoma data is 0.009in, whereas braid comes in at 0.005in – about 45% slimmer,

When you get out to 20lb, the braided line is 0.010in and the mono/fluoro 0.016 in diameter – a difference of 38%.

Braid is a popular line choice for those needing to cast long distances or who need lots of sensitivity to detect bites. Braid is also great to get a good hookset on bony or hard-mouthed fish as it has very little stretch compared to other fishing lines.

Monofilament fishing lines: diameter chart

Spools of line mono braid

Monofilament tends to be slightly thicker in terms of line diameter than fluorocarbon for a given breaking strength and significantly thicker than braided lines, as mentioned above.

Mono is great choice as an affordable running line that you can spool on your reel without breaking the bank compared to braid and fluoro.

Fluorocarbon line diameter chart

Spool of fluorocarbon line with soft plastic lures and snap swivels

Fluorocarbon is a little stronger than mono for an equivalent diameter, except when you get to the highing breaking strain category where fluoro is actually thicker for a given strength test than mono as you can see from the table..

For example, at the 4 pound test mark, monofilament line had a diameter of 0.008in and fluorocarbon line 0.007in. At a breaking strength of 12lb, mono was again 1/1000 of an inch thicker in terms of line diameter than fluoro of the same breaking strength.

Once you get to 50lb and 60lb you can see that fluorocarbon line is a little thicker than mono of the same breaking strength.

It is also more abrasion resistant and nearly invisible in the water. That gives a fluorocarbon leader a number of advantages over a monofilament leader in most circumstances. However, it is worth remembering fluorocarbon line is less supple and harder to tie good knots with. It is also significantly more expensive than monofilament fishing lines across every line class.

Final word on fishing line diameters

This data on fishing line diameters was compiled using the very popular Berkley Trilene and Berkley Big Game (in larged breaking strains) as the mono line, Berkley Vanish as the fluorocarbon line and Spiderwire Stealth as the braided line.


  • Rick Wallace is a passionate angler and fly fisher whose work has appeared in fishing publications including FlyLife. He is a regular on fly fishing podcasts and appeared in the international fly fishing film Predator.

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