Skip to main content

LeaderCalc Articles

Please notice: LeaderCalc hasn't been optimized for small screens. Turning some devices horizontally might make it easier to use, but using a suitably large screen is the best solution.

Leader formulas

In order to calculate the proper formula of a fly fishing leader, you need to understand the basics of leader design.

2 comments

Components of a Leader

There are three main components of a leader: Butt, Taper (also called mid-section or graduation), and Tippet. The most common formula basis for the leader is 60% butt, 20% taper, 20% tippet. Other formulas such as double taper formulas offer 40%,20%,40%, but for the most part, formulas are derivatives of the 60/20/20 rule.
Butt
According to Charles Ritz in his book "A Fly Fisher's Life", the diameter of leader butts should be 60% of the diameter of the end of the fly line. Other formulas indicate that 75% is the optimum butt diameter, but in either case, a leader butt of .017" to .022" satisfies most any formula. A leader butt of 60%-75% is quite ample enough to transmit and disperse casting energy downward to the tippet. Also consider the stiffness of the butt material. It should approximate the stiffness of the fly line.
Taper
Again, Ritz reminds us that the ideal is to have the longest forward taper as possible while still remaining under control during the presentation. He subscribes to the 60/20/20 rule, where the 60% is strength, 20% is taper and the final 20% is terminal tippet.
Tippet
According to Ritz, suppleness in leader material is only necessary at the tippet, where, in his opinion, 20 inches is the ideal length.
Other sub-parts of a leader are: Shock Butt, Shock Tippets and Wire Tippets. These components are geared toward specialty fishing situations like toothy fresh and saltwater critters. This document will not go into great detail in these areas, but you can use the Table below to guide you in selecting the approximately correct tippet thickness for "normal" leaders.

Table
Recommended Fly Sizes for Tippets
(inches)
Diameter
(mm's)
Diameter
X-Rating Fly Size
.003" .08 8X #20-#28
.004" .10 7X #20-#28
.005" .13 6X #18-#26
.006" .15 5X #14-#20
.007" .18 4X #6-#14
.008" .20 3X #6-#12
.009" .23 2X #4-#10
.010" .26 1X #4-#8
.011" .28 0X #4-#6
.013" .33 01X #8-#12
.015" .40 02X #4-#8
.017" .45 03X #1/0-#4
.019" .50 04X #3/0-#1/0
.021" .55 05X #5/0-#3/0

Since you got this far …


The GFF money box

… I have a small favor to ask.

Long story short

Support the Global FlyFisher through several different channels, including PayPal.

Long story longer

The Global FlyFisher has been online since the mid-90's and has been free to access for everybody since day one – and will stay free for as long as I run it.
But that doesn't mean that it's free to run.
It costs money to drive a large site like this.
See more details about what you can do to help in this blog post.

The Global FlyFisher was updated to a new publishing system early March 2025, and there may still be a few glitches while the last bits get fixed. If you meet anything that doesn't work, please let me know.
Martin - martin@globalflyfisher.com