If you fish, you need this knot. Period.
The Uni Knot is a strong and dependable knot used to connect fishing line to swivels or hooks, to connect two fishing lines, and attach fishing line to a reel or a spool.
It’s used by the anglers in both salt and fresh water for joining lines of similar or different strengths.
The best part? It’s incredibly simple to tie, strong, and versatile.
Let’s learn it in detail.
Uni Knot Details
Type: Fishing Knot
Strength: About 80%
Other Names: Duncan Loop Knot, Grinner Knot
ABoK Reference: NA
How to Tie a Uni Knot
- Pass the line through the hook and bring it parallel to your main line.
- Make a big loop by laying the tag end over the doubled line.
- Wrap the tag end around the doubled line 4-5 times.
- Moisten the line and pull the tag end to tighten the knot.
- Slide down the knot to the eyes and cut off the excess tag end close to the knot.
Depending upon the strength of the line you are using, the number of wraps can vary.
Here’s how many wraps you should do depending on your line:
- For a thin line, more friction is needed to grip. Go for 6-7 wraps to create that required friction.
- For a thick line (heavy mono or fluoro lines), 3-4 wraps are enough.
- For a braided line, make 7-10 wraps, as braided lines are slippery and need extra friction.
Uni Knot Step by Step

Application and Uses
The Uni knot is so versatile that it can be used for every kind of fishing, from crappie to catfish.
Here’s where you can use it:
- Attach fishing line to hook, lure, swivel, or fly.
- Attach a fishing line to the spool or a reel.
- Join two fishing lines together (we’ll talk about that version later).
Pros & Cons
- Easy to tie and learn.
- Works with every kind of line. Mono, fluoro, and braid.
- Strong (Retains 75% for line to line connection and 80% when attached to lures, hooks or swivels.)
- Your mainline comes straight out of the eye.
- Sleek profile. It does not catch the moss and grass easily.
- Not as strong as Palomar, San Diego Jam or Palomar Knot.
- May limit the free movement of the lures, especially topwater lures and jerkbaits.
- Can be bulky. If you’re using heavy lines or doubling it up, it get a little heavy.
Double Uni Knot (Uni to Uni Knot)
The term Double Uni Knot is actually a misnomer.
There is a version of the Uni Knot where you double the lines and tie a Uni Knot, and it is often referred to as the Double Uni Knot.
In fishing, the Double Uni Knot is used to attach two fishing lines together using two individual Uni Knots.
It’s a bit bulkier but has high knot strength and is highly effective when you need a strong connection.
It works with both smaller and big diameter lines.
Here’s how to tie it:
- Overlap the ends of lines to be joined.
- Starting from the right, double back the line and make 4-5 wraps around both lines and back through the loop.
- Pull the tag end to tighten.
- Repeat the steps with the line on the left, making the same number of wraps.
- Pull the standing ends in opposite directions to slide the knots together.
- Trim both tag ends.
Note: When tying braided lines to mono, make a minimum of 5 turns with the mono and 6-8 turns with the braid.
Quick History
The Uni knot was invented by Norman Duncan in the early 1960s. That’s why it’s known as the Duncan Knot.
Later on, Viv Dunaway published it under the name Uni Knot.
The name Uni Knot refers to the versatile knot that can be used with monofilament, braid, or fluorocarbon lines.
In England, this knot is known as the Grinner Knot.
In the Ashley Book of Knots, a similar knot is mentioned under ABoK #1121. It shows only three turns and is called a Gallows Knot.
So, the next time you’re out there in the water, tie a Uni Knot. You’ll thank yourself when the line goes tight and the fish pulls hard.