What a loop-to-loop connection does
A loop-to-loop connection joins two pieces of fishing line by threading one loop through another and cinching them tight. It is one of the strongest ways to connect a leader to your main line, or to attach backing to your fly line. The connection holds because the loops lock against each other under load, and because each line is tied to itself — the knot does not depend on friction between two different materials.
Anglers use loop-to-loop most often in fly fishing, where it connects the fly line to a leader or tippet. It also works well for joining monofilament to braided line, or for attaching backing to any line that will see hard use. The connection is reliable enough that many commercial fly lines come with a loop already tied at the end.
Key Takeaways
- A loop-to-loop connection requires that both lines have a loop at the end, made by tying a small knot and folding the line back on itself.
- You thread one loop through the other, then pull the standing line through the loop you just created, and tighten by pulling both lines away from each other.
- The connection is stronger than most knots because the loops lock under tension rather than relying on friction between materials.
- This connection works best when both loops are roughly the same size and the lines are not drastically different in diameter.
How to tie the loops at the end of each line
Before you can make a loop-to-loop connection, each line needs a loop at its end. The standard way is to tie a small overhand knot about half an inch from the end of the line, then fold the short end back and tie another overhand knot around the doubled line. This creates a small loop between the two knots.
Start by tying the first overhand knot loosely — you will thread the line through it again. Leave the short end sticking out. Fold that short end back along the main line, creating a small loop. Tie a second overhand knot around both strands of the loop, cinching it tight. Trim the short end close to the knot. The loop should be small enough to fit through your fingers, roughly the size of a pencil eraser or smaller.
If your line is very thin or slippery, tie the second knot a little tighter and consider making it a double overhand knot — wrap the line around twice before pulling it through. This keeps the loop from slipping under load.
Step-by-step: threading and tightening
Once both lines have loops, the connection itself takes only a few seconds. Thread one loop completely through the other — it does not matter which goes through which. Pull the loop you just threaded through far enough that you have room to work.
Now thread the standing line (the main part of the line you just pulled through) back through the loop that is still stationary. You have created a second loop with the standing line. Pull both standing lines away from each other — one in each hand — and the loops will cinch tight. The connection should be snug and symmetrical, with both loops locked against each other.
Tighten slowly and feel the knots seat. If the loops are not the same size, the smaller one may flip inside out as you tighten — this is normal and does not weaken the connection. Once tight, the loops should not slide or rotate.
When loop-to-loop works best
This connection shines when you are joining lines that will see repeated stress or when you want to change leaders without cutting your fly line. Because the loops lock rather than slip, the connection holds even if the lines are slightly different in diameter. It is also easy to undo — you can reverse the tightening and separate the loops without damaging either line.
Loop-to-loop is less ideal when one line is much thicker than the other. If you are connecting a heavy backing to a thin fly line, the loops may not cinch evenly, and the thinner line can slip. In that case, a nail knot or an Albright knot may hold better. Similarly, if you are working with very stiff line or wire, the loops may not fold neatly enough to lock properly.
Testing the connection before you fish
After you tie a loop-to-loop connection, test it by pulling hard on both lines. The connection should not slip or slide. If it does, the loops were not tight enough or one of the initial knots was not cinched properly — untie and retie.
A good test is to hold the connection in one hand and pull the standing line with the other, hard enough that you feel real tension. The loops should stay locked. If you are connecting a leader to your fly line, you can also cast a few times and feel whether the connection passes smoothly through the guides. A well-tied loop-to-loop should feel almost like a single line.
Common mistakes and how to avoid them
The most common error is making the initial loops too large. A loop the size of a quarter or bigger will not cinch tightly and may slip under load. Keep both loops small — they should be just large enough to thread through each other easily, roughly the size of a dime or smaller.
Another mistake is not tightening enough. Many anglers pull the standing lines gently and stop when the loops touch. Keep pulling until you feel real resistance and the knots are completely seated. The connection should feel solid and immobile.
A third error is using this connection with lines that are drastically different in diameter — say, 20-pound backing and 2-pound tippet. The loops will not cinch evenly, and the thinner line can slip. For extreme diameter differences, use a nail knot or an Albright knot instead.
Frequently Asked Questions
Can I use a loop-to-loop to connect fly line to tippet?
Yes, and it is one of the most common uses. Tie a loop at the end of your fly line and at the end of your leader or tippet, then connect them. The loop-to-loop holds well and lets you change leaders quickly without cutting your fly line.
How long should the loops be?
Keep them small — roughly the size of a dime or smaller. A loop that large is easy to thread and will cinch tightly. Larger loops do not lock as well and may slip under load.
What if one loop is much bigger than the other?
The connection will still hold, but it may not cinch evenly. The smaller loop will lock first, and the larger one may fold or flip as you tighten. This is normal and does not weaken the knot, but if the size difference is extreme, consider using a nail knot or Albright knot instead.
Can I reuse a loop-to-loop connection?
Yes. Unlike most knots, you can untie a loop-to-loop by reversing the tightening, and both lines will be unharmed. This makes it ideal for changing leaders or backing without cutting your fly line.
Is loop-to-loop stronger than a clinch knot?
Yes, loop-to-loop is generally stronger because the loops lock under tension rather than relying on friction between two different materials. It is one of the strongest ways to join two lines, especially when both lines are similar in diameter.