Loop-to-Loop Connection
Quick Answer
To tie a loop-to-loop connection, pass one loop through the other, then pass the terminal end of the second line through the first loop, and pull both standing lines tight. The two loops interlock in a square configuration. It is the fastest and most practical connection for modern fly fishing leader to fly line joins, and works anywhere two pre-formed loops meet.
The Loop-to-Loop Connection is the fastest method for joining two sections of fishing line that have been pre-formed into loops. It requires no tools, takes three seconds to complete, and is fully reversible — making it the universal standard for fly fishing leader-to-fly-line joins and a core technique in offshore big-game rigging.
Unlike a true knot, the loop-to-loop connection does not create a new weak point in the line. Its strength is equal to the strength of the weaker of the two loops used. Properly formed loops — particularly a Bimini Twist — are 100% of line strength, making the loop-to-loop system the strongest possible connection in fishing.
How to Tie the Loop-to-Loop Connection
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Hold one loop in each hand — for example, the welded loop at the tip of a fly line and the Perfection Loop at the butt of a leader.
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Pass the fly line loop through the leader loop (or vice versa — it doesn’t matter which goes first).
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Pass the entire terminal end of the leader — including the full leader, tippet, and fly — through the fly line loop. (In offshore fishing, pass the entire leader through the main line’s Bimini loop.)
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Pull both standing lines — fly line and leader standing section — away from each other. The two loops will seat against each other in an interlocked square.
Critical check: The finished connection should look like a square knot when viewed from the side. Each loop should cross the other at right angles. If one loop simply wraps around the other (a girth hitch), untie and redo it — a girth hitch can lose 30-50% of the connection’s strength.
Applications by Fishing Type
Fly Fishing — Leader to Fly Line
The most common use of the loop-to-loop connection. Modern fly lines have factory-welded loops at the tip. Leaders are sold with pre-formed loops or have a Perfection Loop or Surgeon’s Loop tied at the butt. The connection swaps in seconds when changing from a 9-foot 4X to a 12-foot 6X leader mid-day.
Offshore — Double Line to Leader
In offshore big-game fishing, the main line is doubled using a Bimini Twist to create a large loop. This loop is then connected loop-to-loop to a smaller loop at the end of the shock leader. This system is used for billfish, tuna, and other large pelagic species where the double line provides extra strength at the critical connection point.
Leader Systems — Interchangeable Rigs
Many saltwater and freshwater anglers build modular leader systems with loops at each end, connecting sections loop-to-loop for fast swaps. For example, a bass angler can carry several fluorocarbon leaders with loop ends and swap from a 10lb finesse leader to a 20lb heavy-cover leader in seconds rather than retying.
How to Form the Loops
| Method | Strength | Best for |
|---|---|---|
| Perfection Loop | ~90% | Fly leader butt loops |
| Surgeon’s Loop | ~85-90% | Quick field loops in mono/fluoro |
| Bimini Twist | ~100% | Offshore double-line loops |
| Spider Hitch | ~100% | Quick offshore double-line loops |
| Factory welded loop | ~100% | Fly line tip loops |
Related Guides
- Loop-to-Loop vs Nail Knot — when to use each for fly line to leader
- How to Set Up a Fly Fishing Leader — complete fly leader system
- Best Knots for Fly Fishing — all fly fishing connections
- Bimini Twist — creating 100% strength double-line loops for offshore