There are a number of factors involved in choosing the proper fly fishing line.

  • Line weight
    • Fly fishing line weight is ranked from 1 to 15, with 1 being the lightest and 15 the heaviest
    • Lighter lines are suited for delicate presentations and for casting light flies
    • Heavier lines are best for casting large, wind-resistant and heavy flies
    • Line weight is the easiest to select since this should be matched to your rod and reel
    • Fly fishing requires a balanced system so match the reel and rod. If you don't, you will hurt your casting accuracy and efficiency.
    • A 5 weight reel matches up with a 5 weight rod, so it follows that you should select a 5 weight line
    • Some manufacturers give a leeway by saying you can go one above or below this, say a 4 weight or 6 weight line with a 5 weight reel and rod. If you want to be safe, though, match the line, rod and reel exactly.
    • Your fly fishing line weight should also be selected based on the fish you want to catch
    • You'll need line weights from 1 to 7 lbs for lighter fish such as panfish and most trout
    • Bass need a little heavier weight, from 7 to 9 lbs
    • Larger freshwater and saltwater fish take the heaviest lines an 8 to 15 lbs
  • Line taper
    • To help you cast more efficiently most fly lines are tapered. This taper varies in weight, diameter and thickness over the length of the line.
    • There are five main types of taper, each to meet a specific purpose
    • The taper is listed as an abbreviation by the manufacturer, with the usual abbreviations included in the following discussion:
      • Weight-forward (WF) taper
        • These are the most popular and the best choice if you are a beginner
        • The first 30 feet or so of line is heavier because of its tapered front end
        • The rest of the line is thinner and is known as the running line
        • The weight-forward line helps with long casts and better precision even in windy conditions
      • Bass bug/saltwater (BBT) taper
        • This taper is much like the weight-forward design except that the front section does not run as long
        • This design helps with heavier flies, hence its use for catching feisty bass or bigger saltwater fish
      • Double taper (DT)
        • DT fly lines are preferred by seasoned fly anglers
        • These lines work especially well in making delicate presentations on small- to medium-size rives since the belly is at the center, with both ends gradually tapering
        • This makes the line highly economical too because when one end wears out, you can turn the line around and use the other end
        • This line won't cast as far or provide as much wind resistance as a weight-forward line
      • Shooting taper (ST)
        • ST lines cast farther than other lines so they are designed for fast-running rivers and in extreme wind conditions. The line portion (front section) is stout and short to form a casting loop.
        • Most anglers attach a shooting line on the running line using monofilament, braided line or a very fine diameter fly line
      • Level (L) taper
        • These lines are uniform in diameter throughout, making them the most economical
        • If you are a beginner don't try to save money this way. Level taper lines are the most difficult to cast so they really are best used by seasoned veterans, primarily for fly fishing with live bait.
  • Density
    • How your line behaves on the water depends on its density or line type, which affects its buoyancy
    • With different types of line available, consider buying an extra spool when you purchase your reel. That way you can spool various types of line and switch lines to meet conditions.
    • There are four choices, and each carries an abbreviation, included below, to identify its density:
      • Floating (F) lines
        • These do as they say they float on the water's surface
        • Floating lines are good for beginners since they are easier to cast and handle
        • Floating lines also are a must for dry flies, but they can also work with wet flies, nymphs and streamers that are fished several feet below the surface
      • Intermediate (I) lines
        • These are a little denser than water so they sink slowly to present a fly just below the water's surface
        • These lines work well in shallow, weedy lakes and in choppy waters where you want your line to stay below the choppiness
      • Sinking (S) lines
        • These lines do the opposite of floating lines they sink
        • They are designed for deep lakes and deep, fast-flowing rivers
        • Some manufacturers also put a Roman numeral after the S to show how fast their line sinks in inches per second. For example, an S II line sinks about two inches per second
        • These lines are best for wet flies, nymphs and streamers at a constant depth
      • Floating/Sinking (F/S) lines
        • These combine the two characteristics the five foot to twenty foot tip or front portion sinks to present the bait while the balance of line floats on the water
        • Manufacturers display the depth and speed that the front part of the line sinks
        • This floating/sinking line gets your fly down while helping you maintain control, so it's good for fish such as salmon and steelhead
  • Color
    • If you are a beginner, select a highly visible color yellow, orange, lime green and some shades of tan
    • These colors are easier to see on the water when you cast so you can more easily recognize and correct any casting mistakes
    • For sinking lines, you should go with something that's less visible to fish such as brown, olive, dark green or black
  • Backing
    • Fly lines need a thin, high-visibility line tied between the reel spool and back end of your fly line
    • This generally comes in 20-pound to 30-pound test, with 20-pound suggested for fly line weights less than 8 and the 30-pound test for use with 8-weight line or higher
    • Backing performs three critical functions:
      • This adds length to your fly line, which typically runs only 90 feet
      • This then helps you land big, b fish that run with your line. Experts suggest that use at least 100 yards of backing but up to 200 yards for longer-running fish and saltwater fish.
      • This also keeps your reel spool full, making line retrieval faster and minimizing line recoil. (See fly reels.)
  • Leaders
    • To make delicate presentations or another way of letting your fly or other selected lure hit the water like a natural bug you need a special, tapered length of line that connects your fly line to the fly
    • The fly is then tied to the thinnest part of the line called the tippet, which ensures there won't be a big splash that scares away that big fish
    • When you're out on the water, you want several different sizes and lengths of leaders to adapt to changing conditions and fly sizes
    • Leaders come in a system that helps you match the size of the tippet with the weight of your fly
    • The tippet is the end section of your tapered leader, the part that ties to your fly
    • These tippets carry an "X-rating" based on their diameter ranging from 0X to 8X
    • It's a little deceiving because OX is the thickest and best and 8X is the thinnest and weakest. Just remember to think opposite of the number designations.
    • It is important to carry extra spools of tippet material. Each time you tie a fly, you reduce the length of your leader. After half a dozen changes, you probably will have shortened your leader a foot so you can get back to where you started by tying on another foot of tippet.
    • There are two ways to choose a leader:
    • Based on fly size follow these general guidelines:
Determining Your Leader
Leader size Recommended fly sizes
0X fly sizes 2 - 1/0
1X fly sizes 4 - 8
2X fly sizes 6 - 10
3X fly sizes 10 - 14
4X fly sizes 12 - 16
5X fly sizes 14 - 18
6X fly sizes 16 - 22
7X fly sizes 18 - 24
8X fly sizes 22 - 28
  • To help even more, 4X and 5X are used most often for trout, with 3X and 6X close behind
  • Leaders six feet and shorter are best with sinking or sink-tip lines
  • Small streams are perfect for 7 ½ -foot leaders
  • For trout, use a 9 foot leader since this length works well with dry flies, wet flies and nymphs on fast-moving water
  • In slower water where you really need extreme delicacy, use longer leaders 12 feet or more