Hook gauge

A hook gauge or needle gauge is a measuring device used by crocheters and knitters to test the sizes of particular crochet hooks and knitting needles. Hook gauges are usually made of plastic or aluminum and have sizing holes from 2mm to 11mm diameter. A hook gauge also functions as a ruler to test the size of a test swatch of handmade fabric.

Sizing conventions

A hook gauge is the most reliable way to determine the actual size of a tool. Even though most hooks and needles have metric sizing, tool dimensions vary slightly between different manufacturers. Non-metric sizing conventions also change over time. For instance, different sizing charts rate a 4.0mm hook as either a U.S. G/6 or an F/5.

Importance of accurate sizing

U.S. textile craft terminology employs the word gauge in two different ways: as hook gauge in reference to the sizing tool, or as a standalone term gauge to describe the number of stitches in a standard sized sample of work, usually 4" or 10cm. UK terminology refers to the latter as tension. Craft patterns include a gauge or tension measurement and good practice among crafters is to achieve the correct gauge on a sample swatch before embarking on the full project.