Fishing Line Strength Selector
Match your line to the fish and the water. Pick a species, the cover, and your line type for a recommended pound-test and an estimated diameter — the fastest way to spool up with confidence.
Getting the line right
More lost fish come down to the wrong line than the wrong lure. Too heavy and you spook wary fish and kill your casting distance; too light and a good fish breaks you off in the first run. The species range gets you in the ballpark, and the cover adjustment does the rest — lighter and stealthier in open water, tougher around structure.
Once you know the test, pair it with the right rod using the Rod Power & Action Guide, and size your leader with the Leader Length Calculator.
Frequently Asked Questions
What pound-test line should I use?
It depends on the fish and where you're fishing them. Panfish and trout are comfortably landed on 2–8 lb line, most bass fishing lives in the 8–17 lb range, and pike, muskie, or big catfish call for 20–50 lb. The selector starts from the common recreational range for your species, then nudges the suggestion lighter for open water or heavier for thick cover where you need to horse fish out fast.
How does line type change the diameter?
For the same break strength, monofilament and fluorocarbon are close in thickness, while braided line is far thinner — roughly 40% of the mono diameter. The tool estimates diameter from the well-known monofilament relationship (about 0.095 mm times the square root of the pound-test) and scales it for the material you choose. Thinner line casts farther, sinks faster, and lets you pack more onto the spool.
Why does cover matter so much?
Line is a compromise between stealth and strength. In clear, open water, lighter and thinner line draws more bites and casts farther, so the tool leans toward the lighter end of the range. Around wood, rock, or heavy grass, a hooked fish will bury into the structure and abrade your line, so it sizes up — and it's common there to run a braided main line with an abrasion-resistant leader.
Is this a hard rule?
No — treat it as a sensible starting point. The right line also depends on your rod power, reel drag, water clarity, and the exact lure or bait you're throwing. Match the line to the whole setup, and when in doubt on unfamiliar water, err slightly heavier until you learn how the fish behave.
General guidance for choosing line, not a guarantee. Actual line performance varies by brand, knot, age, and conditions — always check your knots and drag before you fish.