How to Tie a Blood Knot: A 5 Step Guide

the blood knot

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In the world of fly fishing, the blood knot holds a place of honor. Known as the barrel knot in some circles, this neatly tied connection between two lines has been around for centuries. Originally used on sailing ships to whip disobedient crew into line, its name is a tribute to its bloody past. Today, we use it not to keep other anglers at bay, but to secure our leader and tippet connections, ensuring our fly fishing leaders taper down smoothly.

Mastering the Blood Knot

blood knot

Tying a blood knot can seem intimidating at first, but with a little practice, it’s as easy as casting your line on a calm day. The following steps will guide you through the process.

Step 1

Start by aligning your two pieces of line, such as your tippet and leader sections, horizontally and side by side, with about 6 inches of overlap.

Step 2

Hold the overlapped section with your thumb and forefinger, creating a gap between the two lines. This gap will serve as the hole for your tag ends later on.

step 4

Step 3

Take the tag end of either the leader or tippet material and wrap it around the other line 5-7 times. Once you’ve done this, slide the tag end through the loop created in step 2. Remember, it doesn’t matter which line you start with; the process remains the same.

Step 4

Repeat the process with the other line, this time wrapping it around the first line 5-7 times in the opposite direction. Slide the tag end through the same loop as the other tag end. Remember to ensure that the tag ends exit the loop from opposite directions. This will result in a well-tied blood knot.

how to tie a blood knot

Step 5

To finish off your blood knot, wet all lines with saliva and gently pull both main lines apart. As you do this, you should see the lines moving towards each other. Keep pulling until they form the blood knot, then pull a little harder to secure the knot. Trim off the tag ends, leaving a bit of line to prevent the knot from slipping, and voila, you have tied a successful blood knot!

A Pro Tip

I always seal my blood knots with UV knot glue for added strength and to prevent the tag ends from catching on my fly rod during casting. A small dab followed by a few moments in the sun results in a smooth, sealed, and cast-friendly blood knot.

Here’s a handy YouTube video illustrating how to tie a blood knot:


Why is it called a blood knot?

The name “blood knot” originates from its historical use. When tied correctly, it’s so tight it appears to be bleeding, hence the term “blood knot.”

Which is stronger: a blood knot or a uni knot?

While both knots have their strengths, the blood knot is generally considered stronger. The uni knot, however, is easier to tie, especially with slippery lines.

When should you use a blood knot?

A blood knot is most often used when connecting two lines of fishing line together, or when attaching a leader line to the main line. It’s also handy for attaching hooks or lures to the main line.

How many turns should a blood knot have?

Typically, a blood knot requires five to six turns of the line around each other. However, depending on the size and type of line used, this may vary.

is the blood knot strong


How strong is a blood knot?

A blood knot is impressively strong, providing 83% of the strength of the diameter of the lines being used. For example, if you’re using a 15lb line, the blood knot would break at 83% of 15lbs, which equals 12.45lbs. Remember, a blood knot involves two different size lines, so always consider the strength of the weaker line.

How can you tie a blood knot quickly?

Practice is key! However, using a matchstick to maintain the loop for the tag ends can speed up the process and make it easier for beginners.

What are blood knots best used for?

Blood knots shine when joining two different size mono lines together, like a leader to a tippet. They’re also useful as stopper knots in sailing. However, they’re not suitable for use with braid lines, so avoid using them for braid-to-braid or braid-to-mono connections.

What are blood knots best used for?


Mastering the art of tying a blood knot is an essential skill for any fly fisherman. With a bit of practice, you’ll find it as easy as casting your line. Remember, the key to a successful blood knot is the correct number of turns and ensuring the tag ends exit from opposite directions. Happy fishing!

If you found this tutorial helpful, don’t forget to check out our series of fly fishing books below. They are packed with more useful tips and tricks to enhance your fly fishing experience.

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