Understanding Yarn Weight: From Bulky to Lace

Welcome to the mysterious world of yarn weight classification! Sometimes it feels like throwing darts blindfolded trying to figure out the size of the yarn you want to use, but hopefully this article will give you a little more understanding. There are many different systems for classifying the weight of yarn, and most of them are subjective with no clear divisions or definitions in the terminology. This discussion is complicated by the fact that yarns classified as the same weight are often vastly different when you look at them.

As knitters though, it's less important for us to know the actual diameter of a yarn than it is to know the way in which it should be knit. Because of this, the classifications that we use are more closely tied to the knitting gauge than to the actual size of the yarn. It's also important to keep in mind that each weight covers a RANGE of gauges and nothing is absolute.

Here's a chart that assembles a lot of the major classification systems into one handy reference. The chart uses the traditional US terms for naming (with a bunch of alternate names that are often used), the CYCA's (Craft Yarn Council of America) number classification system and the wpi (wraps per inch) which is traditionally a spinning and weaving classification, but can be really handy if you've got an unlabeled or coned yarn. WPI can also be helpful if you are holding multiple yarns together as one strand.

This chart also gives a range of stitches per inch, and an estimate of how many yards should be in each 50 gram or 100 gram ball. This can be very useful if a pattern or yarn doesn't tell you what weight you need, but does tell you how many yards are in each ball. (Note: yardage per ball is given for wool and wool-type fibers. Plant fibers like cotton are heavier and therefore have fewer yards per ball for the same weight of yarn)

As you look at a mystery yarn and try to figure out what weight it is, it's good not to count too heavily on just one classification, but if you find that with 2 or 3 of the criteria the yarn falls into a worsted weight, then chances are good it's actually a worsted weight.

Gauge and yarn weights should be used with eyes wide open, knowing that they aren't absolute and should be used as a guideline. What matters most is whether you like the fabric you're making and if you can get the correct gauge required for your pattern.

copyright Miriam L. Felton - 2011