Tackle Index
Knot

Blood Knot for Mono-to-Fluorocarbon Leaders

Monofilament main line or leader to a fluorocarbon leader section of similar diameter.

Last reviewed 26 September 2026 · Editorial policy

At a glance

What this knot is for

Joins
Monofilament main line or leader to a fluorocarbon leader section of similar diameter
Line types
Monofilament to fluorocarbon, matched or close in diameter. A poor choice where diameters differ by more than a size or two, or for either line to braid.

Reach for it when

  • Building a tapered leader that steps down from mono to a fluorocarbon tippet section
  • Joining mono backing to a fluorocarbon leader of close diameter for clearer water
Method

How to tie the blood knot for mono-to-fluorocarbon leaders

  1. 1Overlap the mono and fluorocarbon ends by 15–20cm.
  2. 2Wrap the mono tag end around the fluorocarbon standing line 5 times, then pass it back between the two lines at the centre.
  3. 3Wrap the fluorocarbon tag end around the mono standing line 5 times in the opposite direction, then pass it back through the same central gap from the other side, crossing the mono's tag end.
  4. 4Moisten thoroughly — fluorocarbon needs more lubrication than mono alone to seat without burning.
  5. 5Pull the two standing lines apart steadily and evenly so both sets of wraps close down together and trap the tag ends in the centre.
  6. 6Trim both tag ends close to the knot.
Blood Knot for Mono-to-Fluorocarbon LeadersDiagram: Tackle Index

Work on a flat surface with enough line in your hand to pull the knot down firmly, and check the wraps sit neatly before you trim anything away.

Why it works

  • A neat, low-bulk join between two stretch-different materials when their diameters are matched
  • Long-established as the standard way to step a leader down through materials

Where it lets you down

  • Fluorocarbon's stiffness makes the wraps harder to seat evenly than mono-to-mono, and it is more prone to slipping if tightened dry
  • A surgeon's knot is more forgiving and often preferred when the two diameters are not closely matched
Shop

The tackle this knot ties

The knot itself costs nothing — it joins your line to the tackle you buy. This search shows the general category this knot is tied onto, never a named brand or model.

Shop fluorocarbon leader material
Alternatives

Knots that do a similar job

Surgeon's Knot →Blood Knot →
Used in

Fishing methods that use this knot

Fly Fishing →Float Fishing →
Keep going

More knots worth learning

Improved Clinch Knot →Palomar Knot →Uni Knot →Double Uni Knot →Blood Knot →Surgeon's Knot →Surgeon's Loop →Figure-of-Eight Loop →
Check the rules where you fish
Some waters restrict tackle or methods — barbless hooks, lead sinkers, certain rigs and line types. Confirm the rules of the water you are fishing before you use any rig or knot.