Blood Knot
Blood Knot
The classic line-to-line knot for joining two lines of equal or similar diameter. Strong, compact, and used by fly fishermen for generations to build tapered leaders.
Video by Sportfishing Report on YouTube
About the Blood Knot
The Blood Knot is the standard line-to-line connection for joining two pieces of monofilament or fluorocarbon of equal or similar diameter. Fly anglers have used it for over a century to build knotted tapered leaders from sections of progressively thinner tippet material.
Its symmetric design — five wraps on each side — creates a compact, balanced knot that tests at 85-90% of line strength when properly tied. It's not the fastest knot to tie, but the result is clean, slim, and reliable on any diameter monofilament.
Best Used For
Ideal applications
- ✓ Joining two lines of same or similar diameter
- ✓ Building knotted fly leaders
- ✓ Joining monofilament sections for freshwater
- ✓ Neat, low-profile line-to-line connections
Not ideal for
- ✗ Lines of very different diameters (use Albright or Slim Beauty)
- ✗ Braided line (slips — use double-uni instead)
Step-by-Step Instructions
Follow these 5 steps to tie the Blood Knot. Watch the video above while following along.
Step 1: Cross the lines
Overlap 8 inches of both line ends in opposite directions. Hold the crossing point between thumb and forefinger.
Step 2: Wrap the first line
Take one tag end and wrap it around the other standing line 5 times, moving away from the center crossing point.
Step 3: Hold and thread
Hold those wraps and pass the tag end back through the opening at the center crossing, from front to back.
Step 4: Wrap the second line
Take the other tag end and wrap it 5 times in the opposite direction around the first standing line.
Step 5: Thread and tighten
Pass that tag end through the center opening from back to front (opposite the first). Both tag ends should exit in opposite directions. Wet thoroughly, then pull both standing lines simultaneously to draw the wraps together. Trim both tag ends close.
Pro Tips
- Five wraps on each side — the symmetry is what makes the knot balance under load
- The two tag ends must exit the center loop in opposite directions
- Pull both standing lines simultaneously — not the tag ends
- Wet heavily — this knot binds badly if pulled dry
Common Mistakes
- Both tag ends exiting on the same side of the center
- Unequal wraps on each side
- Pulling tag ends instead of standing lines to tighten
- Using on lines with large diameter differences — knot won't seat evenly