Knot strength and drag.

Worked example

A 20 lb test line tied with a Palomar (90% efficiency) on fresh line: 20 x 0.90 = 18 lb working strength. Drag at 25% to 33% of that is 4.5 to 5.9 lb. The same line with a plain overhand knot keeps only 10 lb, and an old, scuffed line with a Palomar keeps 13.5 lb.

How it works

Working strength = line test x knot efficiency x condition factor. Knot efficiency is the breaking strength with the knot divided by the breaking strength without it. Published pull tests report roughly 70 to 100% for well-tied knots depending on line type (mono, fluorocarbon, braid), wetness and lubrication. The values here are conservative planning figures: Palomar and Trilene 90%, improved clinch, uni and non-slip loop 85%, double uni, blood and surgeon's 80%, Albright 75%, plain overhand 50%.

Drag setting = working strength x 25 to 33%. A drag at about one quarter to one third of the line's breaking strength is a widely used rule of thumb; the drag at the spool increases as line comes off a full spool and with rod angle. Condition factors (fresh 100%, used 90%, scuffed 75%) are allowances, not measurements. Braid knots behave differently from mono, so test them.

Sources and basis: Knot efficiencies are conservative planning values based on the ranges in widely published independent knot-break tests (they vary by line type and test); the 25 to 33% drag guideline is a common rule of thumb. Not a guarantee of breaking strength. Checked 2026-10-05. Planning guide only, not medical or safety advice.

FAQ

How much strength does a knot take from fishing line?

A good knot keeps roughly 80 to 95% of the line's rated strength; a poor one can lose half. The Palomar and Trilene are among the strongest common knots for terminal tackle.

What drag setting should I use?

A common rule is 25 to 33% of the line's breaking strength, so about 5 to 6.6 lb on 20 lb line before any knot loss (4.5 to 5.9 lb if you start from a Palomar knot's working strength). Lower it for light rods, heavy cover considerations, or when you are fighting near the boat.

Does wetting the knot matter?

Yes. Lubricate knots with water or saliva before cinching. Dry friction heats the line and weakens it.

Why use a conservative knot value?

Real knots vary, and the weakest point of the system sets the limit. Underestimating strength is safer than overestimating it.

Is lb test the same as breaking strength?

Roughly. Rated test is the manufacturer's stated strength, and actual breaking strength is often higher when dry and new. Use the rated value for a conservative result.