Crochet Hook Guide

U. S. crochet hook manufacturers can use both numbers and letters as well as metric sizing on their packaging to indicate hook size. Because sizing nomenclature may vary from company to company, it is best to rely on the package millimeter (mm) sizing for an accurate measurement.

Regardless of hook size, you should always complete a gauge swatch using the hook that you intend to use in your project and compare it to the pattern gauge information.  If your swatch gauge is larger than the pattern gauge, redo a swatch using a smaller hook.  Conversely, if your swatch gauge is too small then redo the swatch using a larger hook to obtain the gauge indicated in the pattern.