Uni Knot
Also known as: Duncan Loop (tied loose)
fishing knot
Saltwater anglers reach for the uni knot more often than almost any other single knot precisely because it isn't a one-job knot - the same basic wrap-and-cinch structure ties a hook or swivel to the line, and when two uni knots are tied facing each other on separate lines and pulled together, it becomes a reliable way to join two lines end to end as well. That versatility, more than raw strength alone, is what's made it a staple with both mono and braided line for decades.
The technique is a controlled series of wraps: the line passes through the hook's eye, doubles back to form a loop, and the tag end wraps around both strands inside that loop several times before being cinched down. Getting it right depends on two habits experienced anglers rarely skip - wetting the line before the final pull to avoid friction heat, and sliding the wrapped knot fully down against the hook's eye before locking it tight, rather than leaving it sitting loose partway up the line.
Because the same core mechanic scales to joining two lines (the double uni knot), learning the uni knot effectively teaches two connections for the effort of one, which is a real practical reason it's often one of the first knots taught to new anglers alongside the improved clinch.
Its name reflects exactly this universality - a single tying technique that adapts to several different connection jobs rather than needing a separate specialized knot memorized for each one. Guides teaching new anglers a small, practical knot vocabulary often start with the uni knot and the improved clinch together, since between the two, nearly every common hook, swivel, and line-joining situation on a typical fishing trip is covered.
How to tie the Uni Knot
Pass the line through the hook's eye and double back to form a loop alongside the standing line.
Strength & security
Approx. strength retained: 80-90% of line strength
Its genuine versatility is the real selling point - the same wrap-and-cinch structure works to tie on a hook, a swivel, or (by tying two uni knots facing each other) join two lines, which few other single fishing knots can claim.
Cautions: Leaving the knot loose and not sliding it fully down to seat against the hook's eye before final tightening is a common error that leaves a weaker, sloppier connection than intended.
Alternatives
- Improved Clinch Knot
A more traditional choice specifically for tying on a hook, though it can't double as a line-to-line joining knot the way the uni knot can.
- Double Uni Knot
The two-uni-knots-facing-each-other technique used specifically to join two separate lines rather than attach a hook.
FAQ
Can the uni knot join two lines together?
Yes - tying a uni knot on each line, facing the other, and pulling them together forms what's commonly called the double uni knot, a standard way to join two fishing lines.
Does the uni knot work with braided line?
Yes, it's a popular choice with braid as well as monofilament, though as with any knot in braided line, using enough wraps and cinching it down fully matters more than with mono.
Why is it called the 'uni' knot?
Its name reflects its universality - the same basic wrap-and-cinch technique adapts to tying on a hook or swivel, and to joining two lines, rather than requiring a different specialized knot for each job.
Is the uni knot good for topwater lures that need a loose loop?
Tied slightly loose rather than cinched fully down to the eye, the uni knot forms a serviceable loose loop connection that gives a topwater lure more natural action - though anglers who want a dedicated loop connection more often reach for a non-slip mono loop or similar purpose-built loop knot instead.
Does the uni knot need to be re-tied often?
Not if tied and cinched correctly the first time - like most fishing knots, it holds reliably until the line itself is changed or damaged; it's not a knot that loosens gradually the way some webbing or rope knots can.
How many wraps should the uni knot use for heavy line?
Heavier, stiffer monofilament and most fluorocarbon generally need fewer wraps (around three to four) to seat properly, while light line takes more (five to seven), since thinner line needs the extra wraps to build enough friction to hold under a hard strike.