Yarn weights explained: what 0 to 7 on the label means
The little skein symbol with a number on it is the Craft Yarn Council (CYC) Standard Yarn Weight System. It groups yarns by thickness, from 0 (lace) to 7 (jumbo). A pattern names a weight, and matching it is the first step to a project that comes out the right size.
The chart (crochet)
| Weight | Also called | Crochet gauge (sc / 4 in) | Hook (metric) | Hook (US) |
|---|---|---|---|---|
| 0 Lace | Fingering, 10-count crochet thread | 32–42 double crochets* | Steel 1.4–1.6 mm; regular 2.25 mm | Steel 6, 7, 8; regular B-1 |
| 1 Super Fine | Sock, fingering, baby | 21–32 sts | 2.25–3.5 mm | B-1 to E-4 |
| 2 Fine | Sport, baby | 16–20 sts | 3.5–4.5 mm | E-4 to 7 |
| 3 Light | DK, light worsted | 12–17 sts | 4.5–5.5 mm | 7 to I-9 |
| 4 Medium | Worsted, afghan, aran | 11–14 sts | 5.5–6.5 mm | I-9 to K-10½ |
| 5 Bulky | Chunky, craft, rug | 8–11 sts | 6.5–9 mm | K-10½ to M-13 |
| 6 Super Bulky | Super bulky, roving | 7–9 sts | 9–15 mm | M-13 to Q |
| 7 Jumbo | Jumbo, roving | 6 sts and fewer | 15 mm and larger | Q and larger |
*CYC lists lace-weight gauge in double crochet. CYC calls all of these ranges guidelines only, so your pattern's gauge always wins.
How to use it
- Match the number. If a pattern calls for a #4 medium yarn, start with a #4.
- Then check the label's own hook and gauge. Two #4 yarns can still differ. Our Petite Purl comparison shows #4 chenilles with recommended hooks from 4.5 mm to 6 mm.
- Swatch before big projects. See gauge swatches without the dread.
Kimberly's tip: Names like "worsted" and "aran" overlap, and brands use them loosely. The CYC number and the label's stated gauge are more reliable than the name.
Sources
- Craft Yarn Council: Standard Yarn Weight System (checked Oct 22, 2026)