So you want to know which size crochet hook to use with the yarn you bought for your latest project, but you have no idea where to start. Or let’s say you want to knit a cool project you saw on Instagram and you have the yarn, you just don’t know which needles to buy. Well you’re in luck because the Craft Yarn Council has everything you need to know to choose the right hooks or needles for any project!

Below are tables showing different sizes of knitting needles and crochet hooks in both metric measurements (millimeters) and U.S. size ranges. Refer to this chart to figure out which metric measurement corresponds with which size. Patterns and even yarn labels typically call for a specific size hook or needle to use with a specific project or yarn weight, so these tables will come in handy when you’re trying to figure out what you need for a project.

If you want to crochet with crochet thread or just crochet something really small, we even have sizing for that! Check out the chart below for guidelines on steel crochet hooks.

Needle and hook manufacturers in the United States use both numbers and letters to describe the size of a hook or pair of needles. They also usually include metric sizing for their products in millimeters (as seen in the tables above). Sometimes exact sizing can vary between companies, so if you’re unsure whether two products are the same size, it’s best to rely on metric sizing for the most accurate measurement.

You should always make a gauge swatch and compare it to the gauge information provided in your pattern or on your yarn label to make sure that the project you’re working on will be the right size.

But what if you make a gauge swatch and it’s the wrong size? Well, if your swatch is bigger than the pattern’s gauge, try redoing the swatch using a smaller hook or pair of needles. On the other hand, if your gauge swatch is too small, redo it using a larger hook or pair of needles. Trying these two approaches should get you to the right size so you can begin your project!

Have you ever wondered why hooks and needles come in so many different materials? You can get the same size hook in aluminum, steel, wood and plastic and they all do the same thing, but there are pros and cons to each material. Check out this post on the B.Hooked blog about the pros and cons between the different materials that hooks and needles come in!

Did you know the sizing guidelines for hooks and needles were created by the Craft Yarn Council as part of our Standards & Guidelines? We created these standards for the entire yarn industry to provide uniformity to yarn, needle and hook labeling, and to patterns, whether they appear in books, magazines, leaflets or on yarn labels.

Our goal through these guidelines is to make it easier for industry manufacturers, publishers and designers to prepare consumer-friendly products and for consumers to select the right materials for a project and complete it successfully. You can view our entire Standards & Guidelines document, which was recently updated to include loom knitting and tunisian crochet abbreviations, on our website.