Fishing Line Explained: Mono, Braid and Fluorocarbon
By Alex Clayton · Updated 23 October 2026
Walk into any tackle shop and you’ll face a wall of spools, each claiming to be stronger, thinner or harder to see than the last. Most of that is noise. Fishing line comes in three main types: monofilament (including copolymers), fluorocarbon and braid. Each strikes a different balance of stretch, diameter, visibility and price, and you choose between them by what you’re catching and how you’re fishing, not by the brand on the box.
On Windermere I switch between all three depending on whether I’m float fishing for perch, feeder fishing for bream or lure fishing for pike. No single mono line, braided fishing line or fluorocarbon line covers all of that.
This guide gives you a plain comparison, what the line strength on the label actually means (with real diameters), a species and method table, and how to look after and get rid of old line. For related kit, see our other tackle explainers.
Mono, Braid and Fluorocarbon Compared
One table answers most “which line?” questions before you spend a penny. Find the property that matters for your fishing, then read across.
| Type | Stretch | Diameter for strength | Sinks or floats | Visibility | Abrasion resistance | Ease of knotting | Typical UK uses |
|---|---|---|---|---|---|---|---|
| Mono (nylon) | High | Thickest | Varies by line | Moderate | Fair | Easiest | Float, general coarse, beginners |
| Copolymer | Reduced | Thick | Varies by line | Moderate | Varies by line | Easy | Feeder, carp mainline, tench and bream |
| Fluorocarbon | Low to moderate | Thick | Sinks | Lower | Good | Harder (stiff) | Leaders, hooklengths, snaggy swims |
| Braid | Almost none | Thinnest | Varies (sinking braids exist) | High | Poor to fair | Needs specific knots | Lure, pike, feeder at range |
Mono
Nylon monofilament is the cheap, forgiving default. It’s easy to tie, it behaves on the spool, and its stretch acts as a shock absorber when a fish lunges under the rod tip. At range that same stretch works against you, because it soaks up the strike before it reaches the hook. Mono also weakens with sunlight and age, so it needs replacing more often than braid (see the replacement section below).
Copolymer
A copolymer is a mono-type line blended from more than one material to cut stretch while keeping mono’s easy handling. Gardner GT-HD is a typical example, with the maker claiming reduced stretch. It’s named here as a spec example, not a recommendation. Abrasion resistance and sink rate vary from one copolymer to the next, so read the maker’s description before you buy.
Braid
Braid is woven from ultra-high-molecular-weight polyethylene fibres, sold under names such as Spectra and Dyneema. It’s very thin for its strength and has almost no stretch, so bites register instantly even at distance. The trade-offs: it’s highly visible, dearer, more prone to tangles and wind knots, and needs knots designed for it.
For most coarse and lure work, braid is paired with a leader of mono or fluorocarbon. It’s a poor choice for float fishing.
Fluorocarbon
Fluorocarbon sinks, resists abrasion better than nylon, costs more and is stiffer. It gets its own section after the next one, because its best-known selling point is also its most overstated.
If you’re buying your first spool for general coarse fishing, start with mono or a copolymer. For the head-to-head detail, read braid vs mono in more depth.
Line Strength: What Breaking Strain and Diameter Really Tell You
A 20lb braid can be under half the diameter of an 18lb copolymer from the same maker. Compare lines on the lb figure alone and you miss the number that decides how far you cast and how much fits on the spool.
What the label means
The breaking strain on the spool is the minimum load the line should break at, and good lines often exceed it, according to Angling Direct’s line buying guide. Some makers go further and rate at knot strength. Gardner, for example, says its Hydro-Sink Noir braid is rated that way. Check which method the spool uses before you compare two lines.
The knot is the weak point. Tie carefully, wet every knot before you pull it tight, and trim tag ends neatly. A badly bedded knot can break well below the figure printed on the spool.
Breaking strain vs diameter: real figures
These are maker figures as published by Gardner, checked on 23 October 2026. The lines are spec examples to show the spread, not recommendations.
| Line | Type | Breaking strain | Diameter |
|---|---|---|---|
| Gardner GT-HD | Copolymer | 12lb (5.4kg) | 0.33mm |
| Gardner GT-HD | Copolymer | 15lb (6.8kg) | 0.35mm |
| Gardner GT-HD | Copolymer | 18lb (8.2kg) | 0.39mm |
| Gardner Hydro-Sink Noir | Sinking braid | 25lb (11.3kg) | 0.35mm |
| Gardner Kinetic Outreach Bait-Up Braid | Braid | 20lb (9.1kg) | 0.18mm |
Look at the 0.35mm rows. The same diameter gives you 15lb in copolymer and 25lb in braid. Diameters for a given lb rating also vary between brands, so compare the mm figure on the spool, not just the lb.
Why diameter matters
Thinner line casts further, cuts through wind and flow better and fits more on the spool. Thicker line resists abrasion better and copes with rough handling. Pick thin for range and open water, thicker for snags and rough ground.
Hooklength vs mainline
Your hooklength should be lighter than your mainline. If you snag, the hooklength breaks first and you leave far less line in the water, and far less trailing from a fish. See hooklengths and terminal tackle for how that end of the set-up fits together.
The headline comparison: 18lb copolymer at 0.39mm against 20lb braid at 0.18mm. Similar strength, less than half the thickness.
Fluorocarbon Line: Low-Visibility, Not Invisible
If fluorocarbon were truly invisible, why does anyone still catch on mono? Because the visibility edge is smaller than the marketing suggests, and fluorocarbon’s real strengths lie elsewhere.
Why it’s harder to see
Fluorocarbon (PVDF) has a refractive index described as close to that of water, so it shows up less than nylon underwater. It’s also denser than mono, which is why it sinks (Wikipedia’s fishing line overview covers the basics). Retailers don’t even agree on the optical explanation, so treat lower visibility as a small bonus rather than the reason to buy.
Where it earns its money
- Leaders and hooklengths that sink and lie flat on the bottom instead of looping up off the lakebed.
- Abrasion resistance around snags, gravel bars and mussel beds.
- Stiffness, which helps some rigs resist tangling on the cast.
That stiffness has a cost. Knots are harder to bed down, so wet them and tighten slowly.
Where it doesn’t
As a full mainline on a float set-up, fluorocarbon works against you. Its stiffness and quick sinking make the line harder to mend and the float harder to control, and it costs more per metre than mono. The more common pairing is braid mainline with a fluorocarbon leader: braid’s feel and casting range, with a tougher, less visible section near the fish.
I’ve found a fluorocarbon leader worth having when drop-shotting or lure fishing for perch on Windermere, mainly for the abrasion resistance around stones and structure.
Buy fluorocarbon line for leaders and hooklengths, not because you think fish can’t see it.
Best Fishing Line by Species and Method
Find your fishing in the table below and you have a line type and a starting strength. There’s no single best fishing line. The right one is matched to the fish, the method and the snags in front of you.
The strength bands come from Angling Direct’s beginner’s guide to line and braid. They’re retailer rules of thumb, not standards.
| Species or method | Line type | Typical mainline strength | Notes |
|---|---|---|---|
| Roach, rudd, perch on float or pole | Mono | 1-4lb | Lighter hooklength below |
| Tench, bream, chub, barbel | Mono or copolymer | 5-10lb | Step up for snags and flow |
| Carp | Mono, copolymer or braid | 10lb plus | See the carp line page |
| Pike, lure or deadbait | Braid | 30-40lb braid | Always a wire trace |
| Feeder at range | Copolymer or braid with a leader | As for the species | Low stretch shows bites at distance |
Treat each band as a starting point. Go to the top of it, or the next band up, when the swim is snaggy, the flow is strong or a bigger fish of the species is likely. Drop towards the bottom of it in clear, open water where bites are hard to come by.
Carp
Carp fishing has its own buying decisions (sinking mainlines, colours, spool sizes), so it gets a page of its own. For that, see our pick of carp mainlines.
Pike: mainline vs trace
Pike teeth cut through mono, fluorocarbon and braid alike. Whatever your mainline, a wire trace goes between it and the hooks or lure. That isn’t optional, and it matters more than any choice of mainline.
Braid suits the mainline job. Its lack of stretch helps set hooks at range and lets you feel exactly what a lure is doing. On Windermere I use braid with a wire trace for both lure fishing and deadbaiting for pike.
Bream, perch and the in-between methods
For float fishing for perch, mono is hard to beat because it’s forgiving close in and sits well with a float. For feeder fishing for bream at distance, low-stretch line makes small bites far easier to read on the quiver tip. In my experience, that’s where copolymer or braid with a leader starts to pay its way.
Fish care
Line that’s too light for the fish or the snags is a risk to the fish, not a test of skill. A break-off can leave a fish trailing line and hooks. If you’re losing fish to snags, step up a band.
Braid in one line: best for lure and pike fishing; skip it for float fishing for roach.
Matching Line to Your Reel and Spooling Up
A new spool that tangles on the first cast is usually a spooling problem, not a line problem. Check how it went on before you look anywhere else.
Start with the line capacity printed on the reel spool. It’s usually given as a diameter and a length. Because braid is so much thinner for its strength (see the diameter table above), the same spool holds far more of it than mono of a similar rating. If you’re unsure your reel suits the line you want, read which reel size you need.
When you load it:
- Keep light, even tension on the line as it goes on, so it beds down evenly.
- Fill to just below the lip of the spool. Overfilling throws loops and wind knots; underfilling costs you casting distance.
- Put mono backing under braid. Many anglers do this so the braid doesn’t slip on a bare spool, and it saves buying more braid than you’ll ever cast.
Braid also needs its own knots and usually a leader, as covered in the comparison section above. For the step-by-step method, see how to spool a reel.
If your fishing line keeps twisting, respool before you blame the brand.
When to Replace Fishing Line and How to Dispose of It
A spool left on a sunny windowsill all summer can be weaker than its label before it’s ever been cast. Line wears out before it looks worn.
Ageing
Mono and copolymer degrade with sunlight, heat and use, and they pick up memory (those stubborn coils off the spool). As a rule of thumb, replace mono mainline about once a year, and sooner if you fish a lot. Braid generally lasts longer but frays, so check the end few metres and cut back after any snag. Store spare spools in a drawer or tackle box, out of the sun.
Before every session
Run the last few metres through your fingers. Nicks, rough patches and flattened sections all mean cut it back and retie. Retie after a snag or a big fish too.
Disposal
Never leave line on the bank. Birds and other wildlife get tangled in discarded line. Take offcuts home and cut them into short lengths before binning, or use a line recycling bin at a tackle shop or club where one exists. Check with the Angling Trust or your club for current recycling schemes.
Venue rules
Some fisheries set their own line rules, including on braid and minimum strengths. Check the fishery’s rules before you travel.
Fresh line is the cheapest insurance in your tackle box.
Frequently asked questions
What is the best fishing line for beginners?
Mono. It's cheap, forgiving and the easiest to knot, and its stretch hides small mistakes when playing fish. Pick a strength from the species table in "Best Fishing Line by Species and Method" above, starting at 1-4lb for roach and perch or 5-10lb for bream and tench.
Is braided fishing line better than mono?
Neither is better overall. Braid is thinner for its strength and almost stretch-free, which suits lures, pike and long-range feeder work. Mono is cheaper, more forgiving and better for float fishing. See braid vs mono for the full comparison.
Can fish see fluorocarbon line?
Fluorocarbon is less visible underwater than nylon, but it isn't invisible. Its refractive index is described as close to water's. Its bigger advantages are that it sinks and resists abrasion, which is why it's mostly used for leaders and hooklengths.
What does line strength mean on fishing line?
Line strength, or breaking strain, is the minimum load the line should take before it breaks. Good lines often exceed it, and some makers rate at knot strength. Compare diameter in mm as well, because lines of the same lb rating vary in thickness. See the line strength section above.
How often should I change my fishing line?
Replace mono mainline about once a year as a rule of thumb, and sooner with heavy use or sun exposure. Braid lasts longer, but check the end few metres for fraying and cut back after snags. Always retie after a snag or a big fish.