Crochet Hook Sizes: The Complete Reference Chart
Hook size is measured in millimeters, based on the diameter of the shaft. That millimeter number is the only one that stays consistent across brands and countries — the letters and numbers stamped next to it vary, so treat them as a rough label, not the real measurement.
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US, UK, and metric sizes side by side
| Metric (mm) | US | Old UK | Typical yarn weight |
|---|---|---|---|
| 2.25 mm | B-1 | 13 | Lace / fingering (thread work) |
| 2.75 mm | C-2 | 12 | Fingering |
| 3.25 mm | D-3 | 10 | Sport |
| 3.5 mm | E-4 | 9 | Sport / DK |
| 3.75 mm | F-5 | 9 | DK |
| 4 mm | G-6 | 8 | DK / worsted |
| 4.5 mm | 7 | 7 | Worsted |
| 5 mm | H-8 | 6 | Worsted (the most common beginner size) |
| 5.5 mm | I-9 | 5 | Worsted / heavy worsted |
| 6 mm | J-10 | 4 | Bulky |
| 6.5 mm | K-10½ | 3 | Bulky |
| 8 mm | L-11 | 0 | Super bulky |
| 9 mm | M/N-13 | 00 | Super bulky |
| 10 mm | N/P-15 | 000 | Jumbo |
How to pick a hook when you don’t have a pattern
Check the yarn label first. Most yarn bands list a recommended hook range on the back — that’s your starting point, not a rule. Work a small swatch, roughly 4 inches square, and compare it to the pattern’s stated gauge (usually given as stitches and rows per 4 inches).
- If your swatch has more stitches per 4 inches than the pattern calls for, your stitches are too tight. Go up a hook size.
- If your swatch has fewer stitches, your stitches are too loose. Go down a hook size.
Gauge matters most for anything that needs to fit a body or a specific space — garments, hats, blankets meant for a certain bed size. For amigurumi or small motifs, gauge is more about matching the tightness the designer used (so stuffing doesn’t show through gaps) than hitting an exact measurement.
Why hook material changes how a size “feels”
Two hooks marked the same millimeter size can behave differently depending on material:
- Aluminum is smooth and lets yarn glide fast — good default, can feel slippery with silky or plant-fiber yarns.
- Wood or bamboo has a little more grip, which helps control slippery yarns but slows down the motion slightly.
- Inline heads (the throat is the same width as the shaft) tend to give more consistent stitch height — Susan Bates Silvalume hooks are a common inline example. Tapered heads narrow gradually and are easier to slide into tight stitches, like the top of an amigurumi round — Clover Amour is a common tapered example.
If your gauge swatch comes out consistently off from every pattern you try, the mismatch is sometimes the hook style, not the size — worth testing an inline hook against a tapered one in the same millimeter size before assuming your tension is the problem.
