We’ve had many questions from customers asking what the numbers mean in front of the names of our coned yarns, such as 8/2 Cotton and 2/10 Merino Tencel. I knew Barbara Elkins, founder of WEBS, would be able to explain it well for us. Here’s what Barbara has to say.
Many of the Valley Yarns weaving yarns are named with fractions like 3/2, 20/2, 2/10, etc. The numbers are shorthand for the number of yards to a pound of a particular yarn. We always give you the number of yards per pound (yd/lb.), but if you know what I call the magic numbers, you can figure yardage yourself.

Yarn is sized by the number of yards in a standard one pound skein of yarn, and every type of fiber has its own magic number.
Here are the numbers you need to know:
A standard one pound skein of single ply cotton has 840 yards in a pound (the count).
A standard one pound skein of single ply linen has 300 yards in a pound (the count).
A standard one pound skein of single ply worsted wool has 560 yards in a pound (the count).
To figure the yards/lb. of 3/2 cotton, you multiply 840 (the count) x 3 (the size) and divide by the ply, 2 and come up with 1260, the number of yards in one pound of 3/2 cotton. The yardage of all cotton yarns is derived in this way. The size will be the first number; the ply will be the second number.
To figure the yards/lb. of 20/2 linen, you multiply 300 (the count) x 20 (the size) and divide by 2, (the ply) and come up with 3,000, the number of yards in one pound of 20/2 linen, for example. And like cotton, the size will be the first number; the ply will be the second number.
To figure the yards/lb. of 2/10 merino tencel, you multiply 10 (the size) x 560 (the count) and divide by 2 (the ply) and come out with 2800, the yards/lb. in one pound of 2/10 merino/tencel. Note that worsted count shows the ply number first.
[EDIT: Regarding how the fibers are written–cotton and linen have the size first followed by the ply. Wool has the ply first followed by the size. Unfortunately, not all publications follow this standard. But on our website, we show wool with the size first and the ply second.]
So if you just remember three magic numbers and the fiber they are associated with, you can generally figure the yards/lb. of many of the yarns you encounter.