Published Apr 25. 2007 - 16 years ago
Updated or edited Mar 1. 2024

Leader formulas

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

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.
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. Use the Table below to guide you in selecting the correct leader butt thickness.
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.
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.

Recommended Fly Sizes for Tippets
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


A Fly Fisher's Life by Charles Ritz. Relevant butt dimentions?...

60% of the line diameter it writes. Is this really relevant?

My flyline tips vary from SH #5 0,75mm to DH #12 1,3mm.
60% of 1,3mm is 0,78mm. But 0,55mm is the butt diameter of all LCalc formuals I found for DH. The 75% butt diameter mentioned makes this even more peculiar.
I read that material stiffness is to take in to consideration. And maybe flyline and leader materials changed over time?

The numbers make better sense in smaller flyline diameters. But still many formulas span across 4-5 AFTM classes. Showing little connection to this "60% rule".

I looked up this book on the Internet. It looks very interesting. I better read it. Maybe this is considered a "fly fishermans bible"? But I can not see that the 60% connection to butt diameters applies. And therefore; is this really relevant to us?

Maybe there is something I don't fully understand? I'd love to get my grips arund this matter, simply because I tie leaders.

Johan F.

Martin Joergensen's picture

You are probably right...


I didn't write the article, so I'm not quite sure when I say this: but you are probably right.

The "60% rule" is most likely more a rule-of-thumb to use if you want to have a starting point for a leader. As you have seen, many of the leaders in the system uses quite different formulas and principles, and most of them are based on real life fishing, and many hours of testing and adjusting.

Regarding Ritz' book, it's an older title, and it comes from a time where mono lines were different from what they are now, which may be the reason for these general rules. My experience is that most of the leaders in LeaderCalc will work as they are designed and shown, even though most will not follow Ritz' principles - not even those bearing his name. I have of course only tried a fraction of them, but they all come from reliable sources and have been used for many years by many anglers.



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