The term “worsted weight” does not, in fact, refer to the actual weight of a yarn, nor does it indicate that this particular yarn is the worst (hardy har har). “Worsted weight yarn” is one term for a specific weight of yarn that is thicker than double knit (DK) and thinner than chunky. Basically, when a pattern talks about “weight,” think of it as “thickness” and you’ll get along fine.
Worsted weight yarn goes by other names including #4 yarn, medium weight yarn, afghan yarn, or aran yarn. It is an excellent all-purpose yarn that can be used for knitting anything from sweaters to scarves, blankets, mittens, socks, or hats.
Worsted weight yarn is generally labelled with an image of a skein of yarn with a 4 on it. When you look at the label, you’re likely to see a standardized set of additional symbols indicating the yarn’s gauge and recommended needles. These symbols appear courtesy of the Craft Yarn Council, an organization that represents leading manufacturers of yarn, needles, accessories, as well as magazine and book publishers and industry consultants. The CYC created their yarn standards “to bring uniformity to yarn, needle and hook labeling, and to patterns, whether they appear in books, magazines, leaflets or on yarn labels” and their system has become the gold standard for identifying yarn weights.
The knit gauge range in stockinette stitch for worsted weight yarn is 16-20 stitches = 4 inches. Its crochet gauge range in single crochet is 11-14 stitches = 4 inches. Worsted weight yarn comes in a variety of textures and strengths from delicate, fluffy 1-ply yarn to a smoother, sturdier 4-8 ply yarn. Your ideal choice of yarn will depend on what you’re creating!
The recommended knitting needle size to use with a worsted weight yarn is 4.5-5.5 mm metric (7-9 US). When you use worsted weight yarn for a crochet project, your choice of hook will depend what your intended end product is as well as your own preferences. For example, crocheting worsted weight yarn with an F or G hook (3.74-4 mm) will result in a stiff, tight fabric, excellent for stuffed animals. For a softer, more drapey fabric, consider a larger hook such as an I/J/K hook (5.5-6.5mm).
The name “worsted weight” comes from the village of Worstead in Norfolk County, England. In the 1300s, Worstead was famous for its wool and weaving. Although wool is no longer produced in the village, weaving and spinning demonstrations are still featured in their annual festival.
Traditionally, a worsted yarn is a long-fiber wool yarn with straight, parallel fibers. This creates a smooth, even yarn, as opposed to a fuzzier, short-fiber yarn. That being said, the term “worsted weight” appears to be only slightly related, as it has less to do with the type of yarn fibers and more to do with the thickness of the yarn strand.