How to Tie the Grinner Knot (Uni Knot)

By Alex Clayton · Updated 23 October 2026

The grinner knot ties a hook, swivel or lure to your line with about six turns of the tag end. It is the same knot American anglers call the uni knot, and it also goes by the Duncan loop.

In UK fishing it covers a lot of terminal tackle: eyed hooks on coarse hooklengths, swivels on feeder and carp rigs, snap links on predator traces, and flies to a tippet. Norman Duncan developed it as a fishing knot in the early 1960s, and Vic Dunaway popularised the “uni knot” name in a 1970 book.

To tie it you need about 15cm of tag end and a little water or saliva. The only real decision is how many turns to make, and Step 3 sets that out for your line. For the other knots worth knowing, see our fishing knots guide.

Step 1: Thread the Line Through the Eye and Double It Back

Most fumbled grinners start with a tag end that is too short. You run out of line halfway through the turns and have to start again.

Pass roughly 15cm (6in) of line through the eye of the hook, swivel or lure.
Lay the tag end back alongside the standing line so the two run parallel.

On small hooks (sizes 16 to 20) tied to fine hooklength line, leave a little extra tag. It is easier to grip with cold fingers, and you trim the spare off in Step 6.

By now you should have two parallel lines running back from the eye, with the tag end pointing up the line.

Step 2: Form the Loop Over the Doubled Line

An open loop is the frame you wrap the turns through. Keep it open and the turns lie side by side. Let it collapse and they cross over each other.

Bring the tag end back towards the eye, laying it over the two doubled lines to form a loop.
Pinch the point where the tag crosses the doubled line between finger and thumb.
Hold the loop open to roughly a finger’s width.

The shape resembles a small noose, and The Ashley Book of Knots (1944) lists it as the gallows knot. Keep the pinch in place through Step 3.

By now you should have an open loop beside the two parallel lines, held firmly at the crossing point.

Step 3: Make the Turns (How Many for Your Line)

Six turns is the standard for a grinner knot, but it is not right for every line. Turn count is the one setting you control.

Wrap the tag end around both parallel lines and through the loop, working away from the eye.
Lay each turn beside the last. Do not let one ride over another.

A common rule of thumb in anglers’ guides is fewer turns as the line gets heavier, and more on fine line and braid:

Line	Typical use	Turns
Mono or fluorocarbon under about 6lb	Hooklengths for roach, skimmers and bream	6 to 7
Mono or fluorocarbon, 6lb to 15lb	General mainline for float and feeder	5 to 6
Mono or fluorocarbon over 15lb	Carp and predator leaders	4 to 5
Braid	Lure fishing, some feeder and carp setups	8 to 10

Braid is where advice splits. Some guides call the grinner unreliable on it; others say 8 to 10 turns hold. Braid is slippery, so use the top of that range and test the knot in Step 6, or tie the Palomar knot for hooks and swivels on braid.

Treat fluorocarbon like mono of the same breaking strain, but take extra care wetting it in Step 4.

By now you should have the right number of neat, uncrossed turns inside the loop.

Step 4: Wet the Knot and Snug the Turns

A grinner can look perfect and still part the first time a fish leans on it. The usual cause is tightening it dry, which heats and weakens the line through friction.

Wet the turns with water or saliva.
Pull the tag end steadily, not with a jerk, so the turns close into a tidy coil around the doubled line.

Check the turns sit side by side. If one has jumped over another, cut the knot off and retie.

Line that curls, looks rough or has gone whitish at the knot has been damaged. Retie it. That takes seconds, and a lost fish costs more.

By now you should have a compact coil sitting a centimetre or so up from the eye.

Step 5: Slide the Knot Down and Seat It

The grinner is a sliding knot, so you seat it by pulling the standing line, not the tag.

While the knot is still wet, hold the hook or swivel.
Pull the standing (main) line so the knot slides down to the eye.
Finish with a firm, steady pull to bed it tight.

With a lure, you can stop just short of the eye to leave a small loop so the lure moves more freely. A hard pull will close it up.

Two mistakes stop the knot sliding or seating cleanly: letting it dry out before you slide it, and pulling the tag end instead of the standing line.

By now you should have a knot snug against the eye with the turns still neat.

Step 6: Trim the Tag and Test the Knot

The grinner is commonly credited with 70 to 90 percent of line strength, but the pages quoting those figures do not cite a test. How well you tie it matters more than the number.

Trim the tag to about 2 to 3mm with line clippers.
Hold the hook safely, by the bend or with forceps, and give the line a steady pull close to the load you will fish at.
If it slips or breaks, retie with an extra turn.

Common faults and fixes:

Slips: too few turns, or braid. Add turns or switch knot.
Breaks at the knot: tied dry, crossed turns, or damaged line.
Will not slide: it has dried out. Rewet it and try again.

To join two lines, use the double grinner knot or the blood knot. For carp hair rigs, tie the knotless knot instead.

Best for: everyday hooks, swivels and lures on mono and fluorocarbon. Skip if: you are tying a hair rig or joining two lines.

By now you should have a trimmed, tested knot ready to fish.

Frequently asked questions

Is the grinner knot the same as the uni knot?

Yes. Grinner knot is the British name and uni knot the American name for the same knot. It is also called the Duncan loop, and some anglers search for it as the universal knot. The steps above apply whichever name you use.

Can you tie a grinner knot with braid?

Yes, with more turns, typically 8 to 10, because braid is slippery. Guides disagree on how reliable it is, so test it with a steady pull before you cast. For hooks and swivels on braid, the Palomar is a common alternative.

How strong is the grinner knot?

It is commonly quoted at 70 to 90 percent of line strength, but the sources quoting those figures do not cite test data. A knot that is wetted, tied with the right number of turns and seated firmly will hold better than one tied in a hurry.

Grinner or Palomar: which is better?

Neither wins outright. The Palomar is often quoted as stronger and suits braid, but its loop has to pass over the hook or lure, which is awkward with big lures. The grinner is quick to tie at the water and adjustable, so it suits most mono and fluorocarbon work.

What is the double grinner knot?

It is two grinner knots tied facing each other, one on each line, then pulled together until they meet. Anglers use it to join mainline to a leader or hooklength. Tie each half with the same turns and wetting as the single knot.