Yarn weight (thickness) determines gauge, yardage per ball, and which projects a SKU suits. For B2B buyers writing spec sheets, comparing factory quotes, or matching marketplace bestsellers, you need a common language across US Craft Yarn Council (CYC) categories, UK ply, metric count (Nm), and gauge.
This chart is a practical reference for procurement and product development.
| Category | Name | Hook (mm) | Needle (mm) | Gauge (sts / 10 cm) | WPI* |
|---|---|---|---|---|---|
| #0 | Lace | 1.4–2.25 | 1.5–2.25 | 32–42 | 18+ |
| #1 | Super Fine / Fingering | 2.25–3.5 | 2.25–3.25 | 27–32 | 14–18 |
| #2 | Fine / Sport | 3.25–3.75 | 3.25–3.75 | 23–26 | 12–14 |
| #3 | Light / DK | 3.75–4.5 | 3.75–4.5 | 21–24 | 11–12 |
| #4 | Medium / Worsted | 4.5–5.5 | 4.5–5.5 | 16–20 | 9–11 |
| #5 | Bulky / Chunky | 5.5–8 | 5.5–8 | 12–15 | 6–8 |
| #6 | Super Bulky | 8–12 | 8–12 | 7–11 | 5–6 |
| #7 | Jumbo | 12+ | 12+ | 0–6 | 1–4 |
*WPI = wraps per inch around a ruler (approximate).
| UK term | US equivalent | Notes |
|---|---|---|
| 2-ply | Lace / fingering | Fine |
| 4-ply | Sport / fingering | Common in UK patterns |
| DK | #3 Light | Double knitting |
| Aran | #4–#5 | Slightly heavier than worsted |
| Chunky | #5 Bulky | |
| Super chunky | #6 Super bulky |
Important: UK "4-ply" ≠ US "4 weight." Always confirm gauge, not name alone.
Nm (metric count) = meters of yarn per gram × 1,000 (higher Nm = finer yarn).
| Approx. Nm | US category | Example use |
|---|---|---|
| Nm 10–20 | Lace / fingering | Fine shawls |
| Nm 5–10 | Sport / DK | Garments |
| Nm 2–5 | Worsted / aran | Sweaters, blankets |
| Nm 0.5–2 | Bulky / super bulky | Quick blankets, chunky craft |
Factory tip: When comparing quotes, ask for Nm, composition, and twist together—two yarns with the same Nm can feel different by fiber.
| US weight | Common ball size | Approx. yardage per 100 g |
|---|---|---|
| Fingering | 50–100 g | 400–480 m |
| DK | 50–100 g | 200–250 m |
| Worsted | 100 g | 180–220 m |
| Bulky | 100–200 g | 100–150 m |
| Super bulky | 200–300 g | 60–100 m |
Use for costing and pattern yardage estimates—not all factories use identical ball weights.
| Retail product | Typical weight |
|---|---|
| Amigurumi / small crochet kits | DK–worsted (#3–#4) |
| Afghan blankets (value) | Worsted–bulky (#4–#5) |
| Premium throw blankets | Bulky chenille (#5–#6) |
| Socks | Fingering–DK (#1–#3) |
| Marketplace gradient cakes | DK–worsted |
| Craft chain bestsellers | Worsted acrylic (#4) |
Include all of the following:
1. CYC category (e.g. #4 Medium)
2. Nm count (e.g. Nm 2.0)
3. Target gauge (e.g. 18 sts × 24 rows / 10 cm, st st)
4. Recommended needle/hook on label
5. Ball weight and yardage tolerance (±3%)
This reduces disputes at inspection.
| If factory says… | Likely US weight |
|---|---|
| Nm 1.8 | Bulky / chunky (#5) |
| Nm 2.5 | Worsted (#4) |
| Nm 5.0 | DK (#3) |
| "8/2 cotton" (indirect) | Fine thread — verify WPI |
When in doubt, request a knit-down swatch at agreed needle size.
Worsted (#4) and bulky (#5) acrylic dominate mass-market knitting and crochet.
Not a 1:1 swap—DK is thinner. Adjust needle size or pattern; expect 20–30% more yardage if substituting DK for worsted.
Roughly bulky/chunky thickness—common for blanket yarn and chenille-type products.
Useful for comparison; elastic fibers (wool, acrylic) can vary—combine WPI with factory gauge data.
Print this chart for buying meetings, attach to RFQs, and align with factory tech packs. Consistent weight specs speed sampling and reduce returns.
Need yarn at a specific weight and Nm? Explore our yarn range or request a quote with your target gauge and ball size.