Standard Yarn Weights

Yarns come in many different thicknesses. We refer to the thickness as the yarn’s weight. Yarns are categorized and grouped by thickness. Each yarn is given a number that represents its group. The chart below shows the classes of yarn weights with their corresponding numbers (as they appear on most yarn labels), the thicknesses encompassed by each group, general information about what gauge the weights of yarn will typically produce, and the recommended hook sizes for each weight (though you may choose to use a different size).

Note: Despite being grouped as the same weight, not all yarns in the same category are exactly the same thickness. There is variation because each group encompasses a range of thicknesses. If your pattern calls for a specific worsted-weight yarn and you substitute it with a different worsted-weight yarn, you may have trouble matching the gauge. If you do, it’s likely because that yarn is a different thickness, and you may need to try another worsted-weight yarn.