Fishing Line Calculator
Find the correct fishing line weight and type for your target species.
Compares monofilament, fluorocarbon, and braid for bass, trout, pike, and saltwater.
Fishing line selection involves matching your line’s breaking strength (test weight), diameter, and material properties to the target species, fishing conditions, and technique being used.
The general sizing principle: Line test strength should typically be 25–50% of the target fish’s maximum weight for experienced anglers using proper technique. Beginners and those fishing heavy cover often choose line rated equal to or above the expected fish weight.
Line test guide by target species:
| Species | Typical Weight | Recommended Test |
|---|---|---|
| Panfish (bluegill, crappie) | 0.5–2 lbs | 2–6 lb test |
| Trout (stream) | 0.5–5 lbs | 4–8 lb test |
| Bass (largemouth, smallmouth) | 2–8 lbs | 8–17 lb test |
| Walleye | 2–8 lbs | 6–12 lb test |
| Catfish (channel) | 5–20 lbs | 12–25 lb test |
| Pike / Musky | 8–30 lbs | 17–30 lb + steel leader |
| Salmon (chinook) | 10–30 lbs | 15–25 lb test |
| Striper bass | 10–40 lbs | 15–40 lb test |
| Tuna (bluefin) | 50–500+ lbs | 50–130 lb test |
Line types and their characteristics:
| Type | Stretch | Visibility | Abrasion | Best For |
|---|---|---|---|---|
| Monofilament | High (25–30%) | Moderate | Good | All-around, beginners, topwater |
| Fluorocarbon | Low (10–15%) | Near invisible | Excellent | Clear water, leader material, bottom fishing |
| Braided | Virtually none | High | Low | Heavy cover, long casts, jigging, deep water |
Diameter matters — thinner line:
- Casts farther
- Sinks faster (better jigging)
- Holds more line on the spool
- Is less visible to fish
Braided line is typically 4–5× stronger than monofilament of the same diameter. A 20 lb braid has the diameter of roughly 6 lb monofilament.
Leader considerations: When using braided line, attaching a fluorocarbon leader (3–6 ft / 1–2 m) offers:
- Near-invisible presentation at the lure
- Abrasion resistance against rocks, teeth, and structure
- Shock absorption (braid has no stretch for hook-sets)
Knot strength — the weakest link: Most line failures occur at the knot, not along the line itself. Poorly tied knots retain only 50–75% of line strength. The Palomar knot is widely considered the most reliable: it retains 95–100% of line strength with braided and monofilament line.
Worked example: Targeting largemouth bass in heavy lily pad cover:
- Expected fish: 3–6 lbs
- Cover: thick vegetation (requires strong hookset, line must resist abrasion)
- Recommendation: 30–50 lb braid (diameter of ~10 lb mono) with a 20 lb fluorocarbon leader
- The braid provides zero-stretch hooksets through the pads; the fluoro leader provides abrasion resistance