Every yarn weight category, the hook size to pair it with, what it's best for, and how the US numbers map to UK terminology.
Crochet yarn weights run from 0 (lace) through 7 (jumbo), with 4 (worsted/medium) being the most common for amigurumi, blankets, and beginner projects. Each weight pairs with a recommended hook size — worsted typically uses a 5–5.5mm (H–I) hook, DK uses 4mm (G), and lace uses 1.5–2.25mm (steel). The Craft Yarn Council ball-band number tells you the weight category at a glance; gauge (stitches per 4 inches) is the most reliable way to verify before starting any pattern.
| Weight # | Name | US term | UK equivalent | Hook size | Stitches per 4" | Best for |
|---|---|---|---|---|---|---|
| 0 | Lace | Fingering / Crochet Thread | Cobweb / 2-ply | 1.5–2.25mm | 32–42 sc | Doilies, fine lace, thread crochet |
| 1 | Super Fine | Sock / Fingering | 4-ply | 2.25–3.5mm | 21–32 sc | Socks, lightweight shawls, baby items |
| 2 | Fine | Sport / Baby | Sport | 3.5–4.5mm | 16–20 sc | Lightweight garments, baby blankets |
| 3 | Light | DK / Light Worsted | DK | 4–5.5mm | 12–17 sc | Garments, baby items, detailed amigurumi |
| 4 | Medium | Worsted / Aran | Aran | 5.5–6.5mm | 11–14 sc | Most amigurumi, blankets, hats, scarves |
| 5 | Bulky | Chunky / Craft / Rug | Chunky | 6.5–9mm | 8–11 sc | Quick-make blankets, scarves, baskets |
| 6 | Super Bulky | Super Bulky / Roving | Super Chunky | 9–15mm | 7–9 sc | Cozy throws, bowls, statement pieces |
| 7 | Jumbo | Jumbo / Roving | — | 15mm+ | 6 sc or fewer | Arm crochet, rugs, oversized accents |
Look for a number inside a yarn-skein icon on the ball band — that's the Craft Yarn Council weight category (0–7). Below the number you'll usually see recommended hook size and gauge in stitches per 4 inches (10cm). When in doubt, the gauge is the truest signal.
You can usually go one weight up or down from the pattern's recommendation if you adjust hook size to match your gauge. Don't substitute across more than one weight — gauge differences compound and finished size will be off.
What is the most common crochet yarn weight?
Worsted weight (#4) is the most common — used for the majority of amigurumi, blankets, and beginner patterns.
Which yarn weight is best for amigurumi?
Worsted weight (#4) cotton is the standard. DK (#3) gives finer detail.
What hook size for worsted yarn?
A 5mm or 5.5mm (US H or I) hook. For amigurumi drop to 4–4.5mm so stuffing doesn't show through.
Is DK the same as light worsted?
Close but not identical. Both are weight #3; light worsted is slightly thicker. Usually substitute cleanly with a hook-size tweak.
What's the difference between worsted and aran?
In US terminology both are weight #4 and largely interchangeable. In UK terminology aran is the heavier end of the medium category.
Can I substitute one yarn weight for another?
Yes, within reason — up or down by one weight category usually works if you adjust hook size and check gauge.