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How to Tie a Nail Knot

Learn how to tie a nail knot to join two lines of different diameters in a smooth, streamlined fashion. The nail knot is one of the most commonly used fly fishing knots for attaching backing to fly line, or when attaching fly line to leader. Start tying a nail knot by following these steps.

When to Use a Nail Knot

The nail knot is one of the best fishing knots you can use when connecting your fly line backing to your fly line, or when attaching your fly line to your leader. This particular knot is popular with fly anglers because it has a smooth, streamlined profile that runs through the guides on a fly rod with little to no resistance.

If you are learning how to fish with a fly rod, the nail knot is one of the essential knots to know.

Nail Knot: Fly Line to Leader Connection

If you decide to use the nail knot as your fly line to leader connection, you can invest in a nail knot tool that will make tying this knot even easier. If you don't have a nail knot tool, you can just use a small plastic or metal tube (such as the barrel of a pen or small plastic straw).

There are a few different fly line knots you can use to connect your fly line to your leader, but the nail knot is a good fly fishing knot to tie when you want to connect two lines of different diameter.

Nail Knot: Fly Fishing Backing to Line Connection

While the nail knot is probably used most often as a fly line to leader connection, it can also be used to connect your fly reel backing to your fly line. Some anglers may prefer to use other fishing knots in this situation (such as the Albright Knot or Arbor Knot), but you should try tying and testing these knots for yourself to determine which works best for you.

Tying a Nail Knot: Follow These Steps

Since you now know when you might want to use a nail knot, follow these steps to tie it.


  1. Place the fly line just beyond the end of the tube. Position the butt end of the leader on top of the fly line.
  2. Wrap the leader around the fly line and tube five or six times (make sure to place the coils close together so that it is easier to close the knot).
  3. Use your fingers to pinch the coils in place, and then insert the tag end of your leader into the tube and push through.
  4. Gently remove the tube, wet the coils, and tighten firmly by pulling on both ends of the leader.
  5. Trim the tag ends if needed.


Congratulations, you just learned how to tie a nail knot! As a next step, you can learn about the best terminal knots for attaching your fly fishing flies to your leader.