Braid to Mono Knots: Double Uni and FG Knot
How to join braided main line to a monofilament or fluorocarbon leader. The double uni is the easy, reliable join; the FG knot is the slim, strongest one.
Braid casts far and has no stretch, but it is visible and weak against abrasion. So most lure anglers fish braid main line with a mono or fluorocarbon leader of about 1–3 m. The join between them has to be strong and slim enough to pass through the rod rings. Two knots cover almost every case: the double uni and the FG knot.
Which knot to choose
Double uni | FG knot | |
|---|---|---|
Difficulty | Easy | Harder, needs practice |
Profile | Medium | Very slim |
Strength | Good | Highest |
Best for | Most fishing, light to medium leaders | Long casting, heavy leaders, guides |
How to tie a double uni knot
Overlap. Lay the braid and the leader side by side, overlapping by about 20 cm (8 in).
Uni knot in the leader. With the leader's tag end, make a loop over both lines and wrap it through the loop around both lines 4–5 times. Snug it.
Uni knot in the braid. With the braid's tag end, do the same in the other direction, but use 8–10 turns — braid needs more grip.
Wet and slide. Moisten both knots and pull the two standing lines apart so the knots slide together and lock.
Trim both tags close.
If you know the uni knot, you already know the double uni.
How to tie an FG knot (overview)
Keep the braid under tension (hold the rod or clamp the braid).
Lay the leader across the braid and make alternating wraps: braid over the leader, then under, about 20 times so the braid weaves a tight sleeve around the leader.
Lock the wraps with two or three half hitches around both lines.
Trim the leader tag, then finish with several half hitches of braid around the braid alone.
Wet and pull hard to bed the wraps.
The FG is worth learning if you cast long distances with a heavy leader; otherwise the double uni is enough.
Tips
Always test the join with a hard pull before you fish.
Leader to braid ratio: roughly 1.5–2× the braid's diameter in mono or fluoro works well.
Replace the leader when it is scuffed — the join is only as strong as the leader.
More on lines and leaders in fishing equipment and every knot guide on the fishing knots page.
