Regular hooks 31 sizes
| mm | US | UK |
|---|---|---|
| 2 | — | 14 |
| 2.25 | B-1 | 13 |
| 2.5 | — | 12 |
| 2.75 | C-2 | — |
| 3 | — | 11 |
| 3.25 | D-3 | 10 |
| 3.5 | E-4 | 9 |
| 3.75 | F-5 | — |
| 4 | G-6 | 8 |
| 4.25 | — | — |
| 4.5 | 7 | 7 |
| 4.75 | — | — |
| 5 | H-8 | 6 |
| 5.5 | I-9 | 5 |
| 6 | J-10 | 4 |
| 6.5 | K-10.5 | 3 |
Regular hooks, continued
| mm | US | UK |
|---|---|---|
| 7 | — | 2 |
| 7.5 | — | — |
| 8 | L-11 | 0 |
| 9 | M/N-13 | 00 |
| 10 | N/P-15 | 000 |
| 11.5 | P-16 | — |
| 12 | O | — |
| 15 | P/Q | — |
| 15.75 | Q | — |
| 16 | Q | — |
| 19 | S | — |
| 20 | — | — |
| 25 | T/U/X | — |
| 30 | T/X | — |
| 35 | Y | — |
Steel hooks (thread) 19 sizes
| mm | US | UK |
|---|---|---|
| 0.75 | 14 | — |
| 0.85 | 13 | 7 |
| 1 | 12 | 6.5 |
| 1.1 | 11 | 6 |
| 1.25 | — | — |
| 1.3 | 10 | 5.5 |
| 1.4 | 9 | 5 |
| 1.5 | 8 | 4.5 |
| 1.65 | 7 | 4 |
| 1.8 | 6 | 3.5 |
| 1.9 | 5 | 3 |
| 2 | 4 | 2.5 |
| 2.1 | 3 | 2 |
| 2.25 | 2 | 1.5 |
| 2.5 | — | — |
| 2.75 | 1 | 1 |
| 3 | — | — |
| 3.25 | 0 | 0 |
| 3.5 | 00 | — |
The letter is a brand’s label, not a measurement. Only E and H mean the same millimeters everywhere — a G is 4 mm from Susan Bates and 4.25 mm from Boye, and the big letters drift further still. The Craft Yarn Council’s own advice: go by the mm on the hook. The UK numbers are for vintage patterns — British hooks have been sold in mm since the 1970s, and UK hooks were numbered differently from UK knitting needles below 4 mm. Steel numbering runs backwards: a bigger steel number is a smaller hook. Starting out? 5.5 mm (US I-9) with medium (4) yarn. Gauge off? Change the hook before you change the pattern: up a size loosens, down a size tightens.