Stitchbay guide
Crochet hook sizes: metric and US letters
Hooks are sized by the diameter of the shaft in millimetres; US hooks add a letter and number (a 4 mm hook is G-6, 5 mm is H-8). Brands can differ by a quarter millimetre at the same letter, so check the millimetres.
| Metric (mm) | US |
|---|---|
| 2.25 | B-1 |
| 2.75 | C-2 |
| 3.25 | D-3 |
| 3.5 | E-4 |
| 3.75 | F-5 |
| 4 | G-6 |
| 4.5 | 7 |
| 5 | H-8 |
| 5.5 | I-9 |
| 6 | J-10 |
| 6.5 | K-10½ |
| 7 | – |
| 8 | L-11 |
| 9 | M/N-13 |
| 10 | N/P-15 |
| 12 | – |
| 15 | P/Q |
| 16 | Q |
| 19 | S |
| 25 | T/U/X |