Crochet hook size chart
Every crochet hook size in millimetres, US letters and old UK numbers, plus which hook to use for each yarn weight.
Crochet hook sizes: mm, US and UK
| Metric | US | Old UK |
|---|---|---|
| 2.25 mm | B-1 | 13 |
| 2.75 mm | C-2 | 12 |
| 3.25 mm | D-3 | 10 |
| 3.5 mm | E-4 | 9 |
| 3.75 mm | F-5 | – |
| 4 mm | G-6 | 8 |
| 4.5 mm | 7 | 7 |
| 5 mm | H-8 | 6 |
| 5.5 mm | I-9 | 5 |
| 6 mm | J-10 | 4 |
| 6.5 mm | K-10½ | 3 |
| 7 mm | – | 2 |
| 8 mm | L-11 | 0 |
| 9 mm | M/N-13 | 00 |
| 10 mm | N/P-15 | 000 |
| 11.5 mm | P-16 | – |
| 15 mm | P/Q | – |
| 15.75 mm | Q | – |
| 19 mm | S | – |
| 25 mm | T/U/X | – |
Sizes in millimetres are the most reliable: US letters and old UK numbers are not always the same between brands. Steel hooks for thread crochet use their own numbering, where a bigger number is a finer hook.
Which hook for which yarn?
| Yarn weight | Also called | Hook | Gauge (single crochet per 4 in) |
|---|---|---|---|
| 0 Lace | Lace, fingering 10-count thread | Steel 1.6-1.4 mm, or 2.25 mm (B-1) | 32-42 dc |
| 1 Super fine | Fingering, sock, baby | 2.25-3.5 mm (B-1 to E-4) | 21-32 sc |
| 2 Fine | Sport, baby | 3.5-4.5 mm (E-4 to 7) | 16-20 sc |
| 3 Light | DK, light worsted | 4.5-5.5 mm (7 to I-9) | 12-17 sc |
| 4 Medium | Worsted, afghan, aran | 5.5-6.5 mm (I-9 to K-10½) | 11-14 sc |
| 5 Bulky | Chunky, craft, rug | 6.5-9 mm (K-10½ to M-13) | 8-11 sc |
| 6 Super bulky | Super bulky, roving | 9-15 mm (M-13 to Q) | 7-9 sc |
| 7 Jumbo | Jumbo, roving | 15 mm and larger (Q+) | 6 sc or fewer |
These are starting points. Amigurumi uses a hook one or two sizes smaller than the ball band suggests for a tight fabric; blankets and shawls often use a bigger hook for drape. See the full yarn weight chart, or turn a photo into a crochet pattern or a C2C graph.
Questions
What size crochet hook do I need for worsted yarn?
Worsted (medium, #4) yarn usually takes a 5 to 6.5 mm hook. 5 mm (H-8) and 5.5 mm (I-9) are the most common. Check the ball band and go up a size if your fabric feels stiff.
What size is an H hook?
An H-8 hook is 5 mm. A G-6 is 4 mm, an I-9 is 5.5 mm, a J-10 is 6 mm and a K-10½ is 6.5 mm.
Why do UK hook sizes go the wrong way?
Old UK sizes came from wire gauges, where a bigger number means a thinner wire, so a UK 8 hook (4 mm) is thinner than a UK 6 (5 mm). Today most hooks are sold in millimetres, which is the safest size to go by.
What if my hook has no size printed on it?
Push it through the holes of a needle and hook gauge: the smallest hole the shaft fits through is its size. Measure the shaft, not the hook head.
How do I know if I need a bigger or smaller hook?
Crochet a swatch and measure it. More stitches per 4 inches than the pattern means your fabric is too tight: go up a hook size. Fewer stitches means it is too loose: go down a size.