If you grew up reading Patrick F. McManus in Field & Stream and Outdoor Life, you probably learned to fly fish with spools of 3X, 4X, 5X, and maybe 6X in your vest pockets. Then, one day, you went to the fly shop to replace a spool or two, and what on earth did you see? Half-sizes. If you were like me, you viewed this as the third sign of the Fly-Fishing Apocalypse. The first being nippers that cost more than a brake job. The second being Euro-nymphing.

As zippers on waders have proven, though, not all innovations are worthy of Walt Kowalski’s front-yard rant in Gran Torino. And I’m here to convince you that half-size tippets are worthy of your respect. To get there, I want you to think about how we hear.

Take a few seconds to hum the first three notes from the scale you learned in grade school.

Do-Re-Mi

If you’re one of those musical unicorns with perfect pitch and you started at middle C, you increased the frequency by 32 Hz when you moved from Do to Re. Then, when you climbed from Re to Mi, you went up by 36. These notes are burned into our memories because the changes from one note to the next sound and feel the same. But 32 and 36 are not equal, and they shouldn’t be. Want dogs to howl and parents to wince? Get a kid to make both jumps 32 Hz at their next recital.

The reason these unequal shifts sound and feel right is because the frequencies change by the same percent. Do-Re-Me starts at 262 Hz, jumps by 12.2 percent to 294, then jumps by 12.2 percent again to get to 330. Our ears care about percentages, much like our financial advisors do for inflation, interest, and market returns. So, the shifts sound the same. There’s a theory or law for everything, and this one is the Weber-Fechner Law.

Even if you’ve never called it by that name, you’ve known about it for most of your life. A five-pound bag of potatoes is half as heavy as a ten-pound bag. A ninety-five-pound Labrador retriever is hardly distinguishable from one that weighs a hundred. Both are five pounds lighter, but the potato sack cut its weight by fifty percent. The Lab, by only five.

So, what does this have to do with half-size tippet? The origin of the X scale for tippet is one of modern society’s unsolved mysteries. Up there with the number system for pencils, Caps Lock where Ctrl should be, and wiener dogs. Please, don’t send hate mail. I love wiener dogs. But, you have to admit, someone had fun making up the story of their origin. Flushing out badgers? Yeah, right.

The X size for tippet specifies its diameter in thousandths of an inch. In a sane world where high priests weren’t inventing languages to keep the unwashed out of the castle, a tippet whose diameter was 4 thousandths of an inch would have a 4 somewhere in its designation. One with a diameter of 6 thousandths of an inch would have a 6. But in our world, where a mile is 5,280 feet and 72 points make an inch, a tippet with a diameter of 4 thousandths of an inch is called 7X. One with a 6-thousandths-inch diameter is called 5X.

Fortunately, if your ciphering skills are adequate, you don’t need a Secret Society decoder ring to figure this out. The tippet’s X number tells you what to subtract from 11 to determine its diameter in thousandths of an inch. As a consequence of this unnecessary conversion, though, you have to use 10X for your size 46 gnat on the Henry’s Fork because, tragically, 11X can’t exist in this system.

To see the problem with our old standard, let’s think about the extremes first. The difference between 1X and 2X tippet looks like this:

1x and 2x tippet diameter compared (illustration: Tim Schulz).

You can see the difference, but one isn’t twice as wide as the other, like it is when we compare 9X to 10X:

9x and 10x tippet diameter compared (illustration: Tim Schulz).

For the thick stuff, 1X is about 11 percent thicker than 2X. For the thin stuff, 9X is 100 percent thicker than 10X. For wind resistance, pliability, and breaking strength, these differences are not the same. Switching by a single X designation depends on where you are on the scale. The standard transitions from 7X to 2X increase the diameter by 25, 20, 17, 14, and 13 percent for each transition.

So, how would we pick the sizes if we believed percentage changes mattered more than absolute ones? An equal temperament approach to tippet notes, so to speak.

Let’s use what we call 4X as our version of middle A, and keep its diameter at 7 hundredths of an inch. We’ll make the scale for our transitions 7 percent, so the next thickest tippet would be 7 percent larger, or 7.49 hundredths of an inch. If we convert that to its X number, we get roughly 3.5X. Going in the other direction, we get 6.54 hundredths, or approximately 4.5X. Sticking with X units for our tippet, our new scale from roughly 2X through 6X would be:

1.8X, 2.4X, 3.0X, 3.5X, 4.0X, 4.5X, 4.9X, 5.3X, 5.7X, 6.0X, and 6.3X

Not too different from 2X, 2.5X, 3X, 3.5X, 4X, 4.5X, 5X, 5.5X and 6X, is it? If we defined our scale with 8 percent changes, we’d get something similar in spirit:

1.5X, 2.2X, 2.8X, 3.4X, 4.0X, 4.5X, 5.0X, 5.4X, 5.9X, 6.2X, and 6.6X

Maybe they’re on to something. Perhaps the tippet manufacturers haven’t created the equivalent of cherry, vanilla, peach, mango, cinnamon, and coffee Coke. Maybe they’re just doing what should have been done long, long ago. So, go ahead, get yourself a tippet caddy wide enough for eight spools, and fill it up. And while you’re at the shop, check out those new 5.73 weight rods and lines. I hear they really sing.