2-Ply and 3-Ply: By the Numbers

By Amelia © January 1, 2026

When teaching plying I usually pass along a few facts about 2-ply vs. 3-ply:

• From the same single, the 3-ply will be thicker than the 2-ply — yeah, this one is pretty obvious.
• From the same single, the balanced 3-ply will have a steeper twist-angle than the balanced 2-ply — less obvious, but consider that 3 singles are contributing twist in the 3-ply, but only 2 singles contribute in the 2-ply.
• From the same single, to the same finished weight, you will get less finished yards in the 3-ply than in the 2-ply — also fairly obvious, since you are taking 3 at a time rather than 2 at a time.

Recently, I got to do a little exercise in 3-ply vs. 2-ply as I was preparing singles for my class Spindles Can Ply! at SOAR and SAFF this year. I had extra color kits from another class so I used them to play some color games with known weights of fiber — I had a ½ ounce ball of each color. Now, do note, I was chain plying one of the balls of singles — it's a structural 3-ply for the purposes of our comparison.

Here are the turtles, all spun up:

In pairs, left-to-right these are:

• 3-ply solid color
• 2-ply two solid colors — often called "barberpole"
• 3-ply keeping color changes clean (remember, it's a chain ply)
• 2-ply with fractal plying — one single changes color faster than the other
• 3-ply candystripe single — two colors spun side-by-side into the single, a 3-ply marl
• 2-ply candystripe singles — a 2-ply marl
• 3-ply keeping color changes fairly clean
• 2-ply with the same color orders — I usually call this "spinning to the grist" — if spun the same, all color changes are clean; that almost never happens so there is heathering as colors change at different times

Whew! When I spun the singles, I mostly tried to keep the diameter the same in the "pairing" of singles for 3-ply and 2-ply. That way I only had to think about one goal while spinning the singles for both. I tried to spin the first lot, the solid colors, thicker; and all the others just aimed for a comfortable default diameter for the NZ corriedale — the fiber I was spinning.

Each ball of singles was ½ ounce, so I had ½ ounce balls of 3-ply and 1 ounce balls of 2-ply.

To compare apples to apples for finished yards, I'm taking half the measured yards of the 2-ply, or a ½ ounce of it, as shown in the table.

Colors	½ ounce 3-ply	½ ounce 2-ply	ratio 3:2
greens	12	19	63%
reds/camel	26	32	81%
green/lime/yellow	22	30	73%
blue/yellow	24	37	65%

As you can see, there is a fair range here in comparing, 63% to 81%. But it does show, even with these small ½ ounce samples that the 3-ply (chain ply in this case) will result in shorter skeins from the same / a similar single than the 2-ply. The average was 70%, or to put it another way, 30% shorter.

If you consider how folding shortens things, take 12 inches as a starting point. Folded in 2, it would be 6 inches; folded into thirds it would be 4 inches, or 67% the length of the 2-fold. So we can see that plying is a bit like folding. Why doesn't it match?

Some of that is due to the imperfection in the singles — I definitely was not aiming for perfect singles so there is some variability in the yarn diameter. These are fairly moderate twist singles, and we would expect that to impact the finished length as well. It's only too bad I didn't record the length of the singles as well — there's always next time! Then there is the fact that the 3-ply would have a steeper twist angle than the 2-ply, which means we'd expect it to be even shorter than the folded paper result. We do see that in 2 of the 4 samples — again, I'd put this down to the spinner perhaps being less consistent overall. I did ply to make balanced yarns, and succeeded, as all were wet-finished and shown to be balanced yarns.

What to do with this information? Well, now I have a ballpark number: 3-ply from the same amount and thickness of single as a 2-ply will be about 70% the 2-ply's yardage. Should I collect more data? Sure. Will I? probably not.

Speaking of numbers, I once analyzed a table in Mabel Ross's book Yarn Design for Hand Spinners. This book is so important to me I bought two copies when I realized I'd sold mine in a destash. The table held data about the WPI in singles, 2-ply, and 3-ply yarns. Her numbers were data points presented in the table. I ran ratios and averages, and what that table told me was that I can ballpark finished yarn diameter vs. singles like so:

• A 2-ply is about 1.5 times the WPI of its single.
• A 3-ply is about 2 times the WPI of its single.

Mabel Ross was assuming the same single for both singles in the plying, but I would hazard to guess you could take the average WPI and use this calculation for a ballpark finished yarn diameter. As with most estimates about spinning, the fiber used, the amount of twist used, and the style of finishing of the yarn can all impact the WPI of the result and thus be above or below these ballpark numbers.

I'm curious to know what ballpark numbers you tend to use in your spinning; tell me in the comments, I'd love to hear from you!

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© January 1, 2026 by Ask The Bellwether, posted at http://askthebellwether.com/