- While crochet thread comes in sizes 3, 5, 8, 10, 20, 30, 40 and up, size 10 is the most common. It is known as "bedspread weight," because it is commonly used for bedspreads, tablecloths, place mats, trims and doilies. It's versatile and can be used on large and small projects.
Size 3 crochet thread is the heaviest of all crochet thread. It is nearly as thick as yarn.
Sizes 30 and above
The smaller sizes 30, 40 and up are rarely used, but work well for lacy patterns. Historically, crochet thread came in much finer sizes, down to 200.
Size 100 crochet thread is generally the same thickness as sewing thread.