The following information is adapted from http://www.yarnstandards.com and borrowed from Knittingtoday.com
| Standard Yarn Weight System | ||||||
|---|---|---|---|---|---|---|
| STANDARDS GUIDELINES FOR CROCHET AND KNITTING Categories of yarn, gauge ranges, and recommended needle and hook sizes |
||||||
| Yarn Weight Symbol & Category Names |  |
 |
 |
 |
 |
 |
| Type of Yarns in Category | Sock, Fingering, Baby | Sport, Baby | DK, Light Worsted | Worsted, Afghan, Aran | Chunky, Craft, Rug | Bulky, Roving |
| Knit Gauge Range* in Stockinette Stitch to 4 inches | 27–32 sts | 23–26 sts | 21–24 st | 16–20 sts | 12–15 sts | 6–11 sts |
| Recommended Needle in Metric Size Range | 2.25— 3.25 mm | 3.25— 3.75 mm | 3.75— 4.5 mm | 4.5— 5.5 mm | 5.5— 8 mm | 8mm and larger |
| Recommended Needle U.S. Size Range | 1 to 3 | 3 to 5 | 5 to 7 | 7 to 9 | 9 to 11 | 11 and larger |
| Recommended Machine Tension LK=Silver
Reed LK150 |
LK 1-3 | LK 3-5 ISM 1 USM 1 |
LK 5-7 ISM 2 USM 2-2.5 |
LK 8-10 ISM 3 USM 3-3.5 |
LK EON ISM 4 USM 4 |
LK EON ISM EON USM EON |
| Crochet Gauge* Ranges in Single Crochet to 4 inch | 21–32 sts | 16–20 sts | 12–17 sts | 11–14 sts | 8–11 sts | 5–9 sts |
| Recommended Hook in Metric Size Range | 2.25— 3.5 mm | 3.5— 4.5 mm | 4.5— 5.5 mm | 5.5— 6.5 mm | 6.5— 9 mm | 9 mm and larger |
| Recommended Hook U.S. Size Range | B–1 to E–4 | E–4 to 7 | 7 to I–9 | I–9 to K–10 1⁄2 | K–10 1⁄2 to M–13 | M–13 and larger |
| GUIDELINES ONLY: The above reflect the most commonly used gauges and needle or hook sizes for specific yarn categories. | ||||||