How to Tie a Double Uni Knot (Uni-to-Uni Knot)

Also known as the double Grinner knot, the Double Uni Knot works in both fresh and saltwater anglers for joining fishing lines that are either of the same length and strength or different. 

All you need to do is tie a simple uni knot and double the line twice at the ends to make a double version. This fishing knot can also tie a fluorocarbon leader to the mainline that is braided

Double Uni Knot Tying Instructions

Double Uni Knot

Use these steps to tie this fishing knot:

  1. Begin by doubling the fishing line and pinch it to keep it together and to make passing it through the loop easier.
  2. Take the doubled line through the eyelet and then bring it up the mainline before looping it back down again.
  3. Take hold of the doubled lines, and the folded tag end with different hands and loop it through four or seven times according to how thick the line is.
  4. Bring the lie out the top and then through the mainline. 
  5. Moisten the lines and pull them tight by the loop, making sure that the wraps don’t bunch or cross over each other. They should be placed on top of one another seamlessly.
  6. Pull the mainline and tag simultaneously so that the wraps of the double unit knot slide down to the eyelet.
  7. To make the wraps snug and tight, pull the tag end and loop and to tighten the knot, pull the mainline.
YouTube video
How to Tie a Double Uni Knot
The Double Uni Knot is one of our favorites for joining two lines.


  • Tighten the double uni knot in steps as you create it. It takes practice, but with enough of it, tying this fishing knot will become easier. 
  • A double uni knot is a good option if you are not using a swivel.
  • One of the best tips you can use is to use this reinforced uni-knot to tie tapered leaders and tippets.


  • The double uni knot is not considered a suitable option for braid to fluoro or tying braid to mono leader connections.
  • This uni knot can overstretch mono if tying a braid to mono knot.


  • Double uni knots maintain the strength of the line if it is tied correctly.
  • It is simple to tie with enough practice.
  • The double uni-knot does not break easily.

Comparison to Other Fishing Knots

  • The double uni knot is easier to make than the blood knot and other fishing knots.
  • These fishing knots don’t rub against rod guides and don’t loosen like the Alberto knots. 
  • It’s stronger than the Surgeon’s Knots, but you may take more time to tie the former than the latter. 
  • Boasts a better breaking strength, which makes it ideal for braided lines.
  • The double uni knot can be passed more easily through guides than the Albright knots. 


  • It’s an excellent knot for fly fishing.
  • It’s used by anglers to connect braided to mono or fluoro leaders.
  • It can be used on drop-shot rigs efficiently.
  • This uni knot is also often used to join shock leader to mono and for lure casting. 

Tying Hooks

To tie the uni to a hook, thread the line through the eyelet and then double it back and slide it through the hole again to make the double line. Then follow the instructions above. 

Tying Line to Line

The double uni knot and the blood knot are popular knot options that anglers use to tie two fishing lines together. 

Frequently Asked Questions

How do I tie a braid to a fluoro leader?

To join a braid to a fluoro leader, use the double double uni knot. Just double the braid over before tying the knot. 

What is the braid strength of this knot?

The breaking strength of the uni is more than 90% but less than 100%.

What is an alternative knot for the reinforced uni knot?

The nail knot is considered a good alternative to uni, especially for tying a fly line to a leader. A slim beauty knot is also a good option because of its strength and low profile. It is also popular because it can tie slippery braid to a mono leader. Besides these, you can also use the FG knot to connect a leader to the mainline fast.

Jon Stenstrom
Founder & Angler
Jon Stenstrom is a fishing enthusiast. He has over 25 years of fishing experience, and 6 years of spearfishing experience, and is currently learning how to boat. Jon has his Open Water PADI Certification and FII Freediver Level 1 Certification. Jon has traveled the world to fish and dive, most notably in the Great Barrier Reef, Baja Mexico, Thailand, and Malaysia. More Articles
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Articles » Fishing Knots » How to Tie a Double Uni Knot (Uni-to-Uni Knot)