Reference guide
Fishing Line Size Chart
Line is sold by pound test, but what matters on the water is diameter. Braid is roughly a third the diameter of monofilament at the same pound test, so 30 lb braid is about as thick as 10 lb mono. Fluorocarbon sits close to mono, sometimes a shade thicker.
That is why you cannot compare line types by the number on the box: 10 lb of one is not the same line as 10 lb of another.
Line diameter by pound test
Typical diameters in inches. Ranges are wide because diameter at a given test varies between brands and between products within a brand.
| Pound test | Monofilament | Fluorocarbon | Braided line | Notes |
|---|---|---|---|---|
| 4 lb | .007"–.009" | .007"–.008" | — | |
| 6 lb | .008"–.010" | .008"–.010" | — | |
| 8 lb | .009"–.011" | .009"–.011" | — | |
| 10 lb | .010"–.013" | .011"–.013" | .005"–.007" | About the diameter of 2-4 lb mono |
| 12 lb | .012"–.014" | .012"–.014" | — | |
| 15 lb | .014"–.016" | .014"–.016" | .007"–.009" | About the diameter of 4-6 lb mono |
| 20 lb | .017"–.020" | .017"–.019" | .008"–.010" | About the diameter of 6-8 lb mono |
| 25 lb | .019"–.022" | .019"–.022" | — | |
| 30 lb | .021"–.024" | .021"–.024" | .010"–.012" | About the diameter of 8-10 lb mono |
| 40 lb | .024"–.028" | .024"–.028" | .012"–.014" | About the diameter of 10-12 lb mono |
| 50 lb | .027"–.032" | .027"–.031" | .013"–.016" | About the diameter of 12-15 lb mono |
| 60 lb | .030"–.035" | .030"–.035" | — | |
| 65 lb | — | — | .015"–.018" | About the diameter of 15-20 lb mono |
| 80 lb | .034"–.040" | .035"–.040" | .017"–.020" | About the diameter of 20-25 lb mono |
| 100 lb | — | — | .019"–.023" | About the diameter of 25-30 lb mono |
Scroll the table sideways to see every column.
A dash means that pound test is not commonly sold in that line type. Diameters are typical published figures, not a specification: check the spool.
Choosing between mono, fluorocarbon and braid
Monofilament
A single extruded nylon strand. The cheapest, most forgiving line and still the right answer more often than its reputation suggests.
Stretch: High (roughly 15-30%) · Visibility: Moderate underwater · Abrasion: Moderate · In water: Floats or sinks very slowly
Where it wins: Stretch cushions hooksets and head shakes, which keeps treble-hook baits pinned and light-wire hooks from tearing out. Ties easily, handles well on cheap reels, and is the most affordable line by a wide margin.
What it costs you: Stretch costs you bite detection at depth or distance. It absorbs water, weakens with UV exposure, and takes a set on the spool, so it needs replacing more often than braid.
Fluorocarbon
A dense polymer with a refractive index close to water, which makes it harder for fish to pick out.
Stretch: Low to moderate · Visibility: Low underwater · Abrasion: High · In water: Sinks
Where it wins: Low visibility in clear water, good abrasion resistance against rock and shell, and it sinks, which helps get crankbaits and bottom baits down.
What it costs you: Stiffer than mono, so it can be fussy in light tests and on small spinning spools. Costs more. Knots need to be seated slowly and wet or the line will fail at the knot.
Braided line
Multiple fibers woven into a rope. Very thin for its strength and effectively no stretch.
Stretch: Almost none · Visibility: High underwater · Abrasion: High against grass, lower against sharp rock and shell · In water: Floats
Where it wins: Thin diameter means more line on the spool and better casting distance. No stretch gives you direct bite detection and hard hooksets at long range or in deep water. Lasts several seasons.
What it costs you: Highly visible, so it usually wants a leader in clear water. No stretch means a stiff rod and braid together will pull hooks out of soft-mouthed fish. Costs the most per spool and needs specific knots.
How to pick a pound test
- Start from the cover, not the fish. Most break-offs happen against wood, rock, shell or grass rather than from a fish pulling hard. Open water lets you fish lighter than the same species in timber.
- Check the rod. Rods carry a printed line rating. Fishing far above it risks the blank; fishing far below it means the rod will not load properly on the cast.
- Check the reel's capacity. An under-filled spool casts badly. Match diameter to what the spool is designed to hold.
- Clear water pushes you lighter. Line diameter is one of the few variables a fish can actually see. Dropping a size often produces more bites than changing lures.
Leader and tippet sizes
Fly leaders and tippet use X sizes, which describe diameter rather than strength. The rule is straightforward: diameter in thousandths of an inch equals 11 minus the X number, so 5X is .006 inches. Breaking strength at a given X still varies by material and brand.
| Size | Diameter | Typical strength | Typically used for |
|---|---|---|---|
| 0X | 0.011" | 13–16 lb | Bass bugs, pike streamers and large saltwater flies. |
| 1X | 0.010" | 11–14 lb | Large streamers and bass flies. |
| 2X | 0.009" | 9–12 lb | Streamers and heavy nymph rigs. |
| 3X | 0.008" | 7–9 lb | Large nymphs, small streamers, big dries. |
| 4X | 0.007" | 5–7 lb | General trout nymphing and larger dry flies. |
| 5X | 0.006" | 4–6 lb | The default trout tippet for most dry-fly and nymph work. |
| 6X | 0.005" | 3–4 lb | Small dries and clear, low water. |
| 7X | 0.004" | 2–3 lb | Midges and heavily pressured trout. |
| 8X | 0.003" | 1–2 lb | The finest normal tippet; midge fishing in flat water. |
Scroll the table sideways to see every column.
Want a specific answer?
The Line Selector gives you a line type, a pound test and whether this setup needs a leader.
Related guides
- Fishing Hook Size ChartEvery size from #28 to 12/0 with what each one is used for, and why the same number differs between brands.
- Fishing Reel Size ChartSpinning, baitcasting, conventional and fly reel classes with typical line capacity and what each size is for.
- Fishing Rod Size GuideWhat length, power and action each control, and how to read the specs printed on a blank.