It means thickness, not how heavy the ball is
A yarn’s weight category describes how thick the strand is. It is not the weight of the ball. A 50 g ball and a 100 g ball of the same yarn are the same yarn weight.
The eight categories
| Number | Category | Names in the CYC guide |
|---|---|---|
| 0 | Lace | Fingering, 10-count crochet thread |
| 1 | Super fine | Sock, fingering, baby |
| 2 | Fine | Sport, baby |
| 3 | Light | DK, light worsted |
| 4 | Medium | Worsted, afghan, aran |
| 5 | Bulky | Chunky, craft, rug |
| 6 | Super bulky | Super bulky, roving |
| 7 | Jumbo | Jumbo, roving |
These are broad groups, and some names appear in more than one category. For example, the guide lists “fingering” in both 0 and 1. A category number helps compare yarns but does not guarantee the same stitch size. Compare labels and make a gauge swatch for your project.
Thicker yarn generally needs a bigger hook or needle. See the knitting needle and crochet hook charts.