How do I Know What Leader is and What Size I Need!?

How do I Know What Leader is and What Size I Need!?

You’re just about ready to hit the water, but you still have a couple more things to add to the shopping list. Next is the leader. The leader is the line that’s attached to your colorful fly line and is clear. In the picture below you can see the thick clear line attached to the colored fly line.

Leaders mostly come in two lengths - 7.5 to 9 foot, the length depends on the type of fishing you’re doing. If you’re using dries a long leader is better so the fish don’t spook at the sight of the fly line, same as if you’re euro nymphing. However, if you’re fishing shallow water or indicator fishing a shorter leader is fine. Typically, the length doesn’t matter as much as the “X” size does. Most leaders are monofilament nylon, which means they have a large back end that’s attached to the fly line and then narrows down at the tip. The taper on the leader allows it to shoot through the air more efficiently because of its weight distribution and the tip allows it to land on the water softly. Determining the size of leader you need depends on the flies you’ll be throwing and of course the size of the fish you’ll be catching! Leaders are measured by an “X” rating system which shows how strong and how thick or thin the leader is. When is comes to leader the number next to the X can be tricky because a smaller number = stronger and thicker line. So 0X is very strong and made for large salmon and steelhead while 8X is for small trout.

You can find leader in several different brands and categories depending on the fishing you’re doing. My leader when trout fishing in Colorado will look something like this little package below!

Here’s an awesome chart showing how many pounds (pound test) and fish the leader can hold up to!

Leader Size

Pound Test

Fish Size


25 lb.

Big Game Species


20 lb.

Large Salmon


18.5 lb.

Striped Bass


15.5 lb.

Salmon, Steelhead


13.5 lb.

Bonefish, Redfish, Permit


11.5 lb.

Large & Smallmouth Bass


8.5 lb.

Bass & Large Trout


6 lb.



4.75 lb.

Trout & Panfish


3.5 lb.

Trout – Easily Spooked Fish


2.5 lb.

Trout & Panfish / Delicate Presentations


1.75 lb.

Trout & Panfish / Small Flies

This chunky rainbow was caught on 3x leader and tippet because it’s a bigger fish in a private river that does not spook easily!

Next week we will go over tippet and how to determine what you need!

All Pictures by Black Mountain Cinema 

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