Crochet hook size chart
US letter sizes, old UK numbers and metric crochet hook sizes side by side, with the yarn weights each hook suits.
Updated
Hook size conversion chart
| Metric | US | UK | Yarn weight |
|---|---|---|---|
| 2.25 mm | B-1 | 13 | Lace, Super fine |
| 2.75 mm | C-2 | 12 | Super fine |
| 3.25 mm | D-3 | 10 | Super fine |
| 3.5 mm | E-4 | 9 | Super fine, Fine |
| 3.75 mm | F-5 | — | Fine |
| 4 mm | G-6 | 8 | Fine |
| 4.5 mm | 7 | 7 | Fine, Light |
| 5 mm | H-8 | 6 | Light |
| 5.5 mm | I-9 | 5 | Light, Medium |
| 6 mm | J-10 | 4 | Medium |
| 6.5 mm | K-10½ | 3 | Medium, Bulky |
| 7 mm | — | 2 | Bulky |
| 8 mm | L-11 | 0 | Bulky |
| 9 mm | M/N-13 | 00 | Bulky, Super bulky |
| 10 mm | N/P-15 | 000 | Super bulky |
| 11.5 mm | P-16 | — | Super bulky |
| 15 mm | P/Q | — | Super bulky, Jumbo |
| 16 mm | Q | — | Jumbo |
| 19 mm | S | — | Jumbo |
| 25 mm | T/U/X | — | Jumbo |
How to read hook sizes
The metric size is the diameter of the hook's shaft in millimetres. US hooks use a letter plus a number (G-6, H-8); the letter and number both go up as the hook gets bigger. Old UK sizes run the other way, like UK knitting needles.
If your stitches are too tight or your fabric is stiff, go up half a millimetre. If the fabric has holes you did not intend, go down.
Common questions
What size is an H crochet hook?
An H-8 hook is 5 mm, UK size 6. The standard range puts it with light (DK) yarn, but many crocheters also use it with worsted for a firmer fabric, such as amigurumi or bags.
Which hook should I use for worsted yarn?
The standard range for worsted (medium, 4) yarn is 5.5–6.5 mm, which is I-9 to K-10½. Go down to an H-8 (5 mm) for a denser fabric, or check the hook size printed on your ball band.
What are steel crochet hooks for?
Steel hooks are smaller than 2.25 mm and are used with crochet thread and lace-weight yarn, for doilies and fine lace. They have their own numbering where bigger numbers are smaller hooks.
Is a letter or the mm size more accurate?
The mm size. Brands sometimes put the same letter on slightly different sizes, especially above 10 mm. Match the mm size in your pattern.