There are many numbers and categories that describe yarn and fiber—30/2, eight-ply weight, DK weight, yards per pound—but what do these numbers really tell you about your own yarn and projects?
Sometimes, the numbers have quantitative meaning (grist, count, etc.). Other times, the numbers represent an order or category, not a size (for example, Craft Yarn Council yarn weights). Before we go further, remember the numbers and names associated with fiber and yarn are just guidelines. Use your own hands to decide whether a fiber is fine or coarse, softly or densely spun. Weave a sample to decide whether a yarn is right for your project. Take comfort in knowing that handmade fiber arts projects do not need the same precision as getting an astronaut to the moon and back or for specifying a yarn for a run of 25,000 worsted-wool sweater vests.
Many of the numbers are intended to characterize the thickness or diameter of yarn. However, within each measurement system, you need to be aware of what the numbers mean relative to the yarn thickness. See Figure 1.