How to Tie a Nail Knot: A 4 Step Guide

nail knot

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Mastering the nail knot is a must for any fly fishing enthusiast. This simple yet versatile knot has a myriad of applications in the world of fly fishing. Its origin stems from the tradition of fly fishing, and it gets its name from the original practice of tying it with a nail. However, these days, you can use a nail knot tool for ease and precision.

You can employ a nail knot for various purposes such as connecting your fly line to the leader, fly line to backing, creating or fortifying welded loops on your fly line, or using a double nail knot to join two pieces of line with different diameters for your leader to tippet connection.

How To Tie A Nail Knot

how to tie a nail knot

To begin with, tying a nail knot requires a tool to aid your tying. This can be a nail, the nail knot tool or your nippers, a needle, or a small tube. For illustration’s sake, let’s assume you’re using the nail knot to connect the butt end of your leader to your fly line.

Step 1

Align your fly line, leader, and your chosen tube horizontally in a way that they overlap, with the leader at the top, the fly line in the middle, and your tube, nail, or needle at the bottom. Secure all three of them below the tag end of your leader.

Step 2

Wrap the tag end of your leader material around the fly line and tube back towards the mainline of the leader. Make a minimum of 6 turns for secure knotting.

Step 3

Next, guide the tag end of the leader through all the turns you have just made. This is where using a nail or tube tool makes tying a nail knot a breeze. Pass the tag end through the tube or the gap made by the nail so it comes out the other side.

Step 4

After removing the tube, wet the knot with saliva, and slowly pull the tag end of the mono until it forms smooth coils around the fly line. Now, pull it tight again to ensure the knot is strong and cut off the tag end.

Check out this free video that visualizes the steps.


Is a Nail knot strong?

Absolutely! A nail knot holds exceptional strength and provides 100% knot strength. This means if you tie nail knots with a 20 lbs mono onto your fly lines, they will break at 20 lbs.

What is a nail knot used for?

Historically, a nail knot was the go-to knot for anglers to attach leader or backing to fly lines. Its smooth finish allows it to glide through the rod guides seamlessly. Although the advent of welded loops on almost every fly line has reduced the usage of nail knots, they can still be used to fortify your loop when fishing for larger fish like GT’s that might break the loop. You can also employ a double nail knot to join two lines of different diameters. This knot is my personal favorite when fishing for bigger fish as its breaking strain surpasses that of a blood knot.

How To Tie A Double Nail Knot

how to tie a double nail knot

The process of tying a double nail knot mirrors that of the single one, except you repeat the process twice, once with each of the two pieces of line you’re attaching so that the wraps meet in the middle. It might sound tricky, but it’s actually pretty straightforward.

How do you tie a nail knot without a tool?

While a tool makes the process easier, you can certainly tie nail knots without one. Just follow the same steps as above, ensuring your turns coil up, stay hollow, and aligned. This will make it easier to pull the tag end through at the end.

Is a Uni knot the same as a nail knot?

Is a Uni knot the same as a nail knot?

No, the uni knot and nail knot are two distinct knots. Though they might bear some resemblance and both can be used to join two lines, the uni knot has a different end to it utilizing a loop to secure it.


Mastering the nail knot is an essential skill for any seasoned or aspiring fly fisher. With its versatility and strength, it’s a tool you’ll find yourself using frequently. Now that you’ve learned how to tie a nail knot and its double variant, it’s time to put your newfound knowledge into practice. So grab your gear, hit the waters, and enjoy the art of fly fishing.

And if you’re looking for more tips and tricks to enhance your fly fishing experience, don’t forget to check out our series of fly fishing books below.

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