Hooks and needles are sold in millimeters almost everywhere, but US patterns often use letters for hooks and numbers for needles. Old UK patterns use a different number system again. Use the mm size as your anchor.
| mm | US hook | US needle | Old UK |
|---|---|---|---|
| 2.0 | - | 0 | 14 |
| 2.25 | B-1 | 1 | 13 |
| 2.75 | C-2 | 2 | 12 |
| 3.0 | - | - | 11 |
| 3.25 | D-3 | 3 | 10 |
| 3.5 | E-4 | 4 | - |
| 3.75 | F-5 | 5 | 9 |
| 4.0 | G-6 | 6 | 8 |
| 4.5 | 7 | 7 | 7 |
| 5.0 | H-8 | 8 | 6 |
| 5.5 | I-9 | 9 | 5 |
| 6.0 | J-10 | 10 | 4 |
| 6.5 | K-10.5 | 10.5 | 3 |
| 7.0 | - | - | 2 |
| 8.0 | L-11 | 11 | 0 |
| 9.0 | M/N-13 | 13 | 00 |
| 10.0 | N/P-15 | 15 | 000 |
| 12.0 | - | 17 | - |
| 15.0 | P/Q | 19 | - |
Which size for which yarn? The yarn weight chart lists the usual hook and needle range for each weight. If your gauge is off, go up or down one size and try again with the gauge calculator.
Questions
What size is an H-8 crochet hook?
An H-8 hook is 5 mm. It is a common size for medium (4) worsted yarn.
What is a 4 mm hook in US sizes?
A 4 mm hook is a US G-6. A 4 mm knitting needle is a US 6.
Why do some sizes have no letter?
Not every metric size has a US name. Where the chart shows a dash, use the mm size.
Keep count with Crochet Counter
This chart is in the app too, in the Tools tab. The core app is free, has no ads and needs no account. Pro is optional.
