Worsted weight yarn is a medium weight yarn that sits in the middle of the yarn weight family. It is thicker than sock and sport weight and thinner than bulky weight yarn. In the UK, worsted weight yarn is equivalent to aran weight yarn. The knitting tension for worsted weight yarn is 16-20 stitches. Worsted weight yarn is a popular choice for beginners and winter knits such as jumpers and blankets. It is also great for knitting sweaters, hats, scarves, mittens, and other projects. Worsted weight yarn is usually knitted on 4-5½mm needles. Light worsted weight yarn is the same as DK weight yarn in the UK.

It is important to note that the term "worsted" can also refer to the way the yarn is processed – it can either be worsted spun or woolen spun – so you may see it used in the context of yarn manufacturing and spinning as well.