crochetguidePrintable crochet hook size conversion chart
Print regular and steel hook sizes on separate charts: millimeters first, then US letters and old UK numbers, with sizes that makers label differently marked.
| Millimeters | US label | Old UK |
|---|---|---|
| 2 mm | No standard label | 14 |
| 2.25 mm | B-1 | – |
| 2.5 mm | No standard label | 12 |
| 2.75 mm | C-2 | – |
| 3 mm | No standard label | 11 |
| 3.125 mm | D | – |
| 3.25 mm | D-3 | – |
| 3.5 mm | E-4 | 9 |
| 3.75 mm | F-5 | – |
| 4 mm | G-6 | 8 |
| 4.25 mm | G | – |
| 4.5 mm | 7 | 7 |
| 5 mm | H-8 | 6 |
| 5.25 mm | I | – |
| 5.5 mm | I-9 | 5 |
| 5.75 mm | J | – |
| 6 mm | J-10 | 4 |
| 6.5 mm | K-10.5 | 3 |
| 7 mm | No standard label | 2 |
| 8 mm | L-11 | 0 |
| 9 mm | M/N-13 | 00 |
| 10 mm | N/P-15 | 000 |
| 11.5 mm | P-16 | – |
| 12 mm | No standard label | – |
| 15 mm | P/Q | – |
| 15.75 mm | Q | – |
| 16 mm | Q | – |
| 19 mm | S | – |
| 25 mm | T/U/X | – |
| 30 mm | T/X | – |
Match the millimeter marking on the actual hook. One letter may refer to more than one diameter. Old UK numbers from the DROPS hook chart, checked 2026-10-09.
| Millimeters | US label or labels |
|---|---|
| 3.5 mm | 00 |
| 3.25 mm | 0 |
| 2.75 mm | 1 |
| 2.7 mm | 00 |
| 2.55 mm | 0 |
| 2.35 mm | 1 |
| 2.25 mm | 2 |
| 2.2 mm | 2 |
| 2.1 mm | 3 |
| 2 mm | 4 |
| 1.9 mm | 5 |
| 1.8 mm | 6 |
| 1.75 mm | 4/0 |
| 1.7 mm | 5 |
| 1.65 mm | 7 |
| 1.6 mm | 6 |
| 1.5 mm | 8/7/2 |
| 1.4 mm | 9/8 |
| 1.3 mm | 10 |
| 1.25 mm | 9/4 |
| 1.15 mm | 10 |
| 1.1 mm | 11 |
| 1.05 mm | 11 |
| 1 mm | 12/6 |
| 0.95 mm | 13 |
| 0.9 mm | 14/8 |
| 0.85 mm | 13 |
| 0.75 mm | 14/10 |
| 0.6 mm | 12 |
Steel numbers vary by manufacturer. A number alone may give several possible diameters.
Updated . US stitch terms. Keep the yarn label with your project.