Crochet Hook Size Conversion Chart
| Metric (mm) | US Letter | US Number |
|---|---|---|
| 2.00 mm | Steel 14 | |
| 2.25 mm | B | 1 |
| 2.75 mm | C | 2 |
| 3.25 mm | D | 3 |
| 3.50 mm | E | 4 |
| 3.75 mm | F | 5 |
| 4.00 mm | G | 6 |
| 4.25 mm | G | |
| 4.50 mm | 7 | |
| 5.00 mm | H | 8 |
| 5.50 mm | I | 9 |
| 6.00 mm | J | 10 |
| 6.50 mm | K | 10.5 |
| 8.00 mm | L | 11 |
| 9.00 mm | M/N | 13 |
| 10.00 mm | N/P | 15 |
| 12.00 mm | O | |
| 15.00 mm | P/Q | |
| 16.00 mm | Q | |
| 19.00 mm | S |
Tip: The safest and easiest way to identify hook size is
via the metric system. Sizing tools are available to assist in identifying
hook size where printing has worn off.
Crochet Hook Sizes by Yarn Weight
| Yarn Weight | Typical Hook |
|---|---|
| Lace (0) | 1.5–2.25 mm |
| Super Fine (1) | 2.25–3.5 mm |
| Fine (2) | 3.5–4.5 mm |
| Light (3) | 4.0–5.0 mm |
| Medium/Worsted (4) | 5.0–6.0 mm |
| Bulky (5) | 6.5–9.0 mm |
| Super Bulky (6) | 9.0–15.0 mm |
| Jumbo (7) | 15.0 mm+ |
Choosing the Right Crochet Hook Size
Hook sizes vary from yarn to yarn due to actual yarn size as well as individual gauge and tension. Hook size may need to be adjusted up (bigger) or down (smaller) to achieve the correct gauge.
It’s best to always crochet a test swatch to check your gauge and tension when creating garments. It may not be as important for items such as scarves or wraps where fit is not critical.
A test swatch should be created for every square in the Fibre Arts for the Soul Sampler Afghan to ensure your squares line up when joining. Your Single Crochet Square will be your control square. Creating swatches will also provide practice working each stitch.