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Crochet Hook Size Chart
Convert crochet hook sizes between metric millimetres, US letters, and UK numbers, and see the yarn weight each hook suits. The metric size is the reliable reference, since US and UK systems number their hooks differently.
| Metric | US | UK / Canada | Typical yarn |
|---|---|---|---|
| 2.0 mm | n/a | 14 | Lace, thread |
| 2.25 mm | B-1 | 13 | Lace, fingering |
| 2.5 mm | n/a | 12 | Fingering |
| 2.75 mm | C-2 | n/a | Fingering, sock |
| 3.0 mm | n/a | 11 | Sock, sport |
| 3.25 mm | D-3 | 10 | Sport |
| 3.5 mm | E-4 | 9 | Sport, DK |
| 3.75 mm | F-5 | n/a | DK |
| 4.0 mm | G-6 | 8 | DK, light worsted |
| 4.5 mm | 7 | 7 | Worsted |
| 5.0 mm | H-8 | 6 | Worsted |
| 5.5 mm | I-9 | 5 | Worsted, aran |
| 6.0 mm | J-10 | 4 | Aran |
| 6.5 mm | K-10.5 | 3 | Aran, bulky |
| 7.0 mm | n/a | 2 | Bulky |
| 8.0 mm | L-11 | 0 | Bulky |
| 9.0 mm | M/N-13 | 00 | Super bulky |
| 10.0 mm | N/P-15 | 000 | Super bulky |
| 12.0 mm | O | n/a | Jumbo |
| 15.0 mm | P/Q | n/a | Jumbo |
| 16.0 mm | Q | n/a | Jumbo |
| 19.0 mm | S | n/a | Jumbo |
Sizes vary slightly between manufacturers, and some US letter sizes map to more than one millimetre. When a pattern and your hooks disagree, trust the metric millimetre size, and always confirm against a gauge swatch.
Frequently asked questions
What is the most common crochet hook size?
The 5.0 mm hook, labeled US H-8 and UK 6, is the most common. It pairs with worsted weight yarn, the most popular yarn for everyday crochet, which is why most beginner patterns and kits use it.
How do US and UK crochet hook sizes differ?
US hooks use letters and numbers (B-1 through S), while UK and Canadian hooks use a numbering system that runs in the opposite direction, so a larger UK number is a smaller hook. The metric millimetre size is the reliable common reference between them.
Which hook size should I use for worsted weight yarn?
Worsted weight yarn (CYC 4) usually calls for a 5.0 mm to 5.5 mm hook, US H-8 to I-9. The yarn label gives a recommended size, but always match your hook to your gauge swatch rather than to the label alone.
Does the hook size on the yarn label matter?
The label size is a starting point, not a rule. Your personal tension changes the right hook. Crochet a gauge swatch, and if your stitch count is too tight go up a hook size, or down a size if it is too loose.
What hook do I use for amigurumi?
For amigurumi you use a hook one or two sizes smaller than the yarn label suggests, often a 3.0 mm to 3.5 mm hook with worsted or amigurumi cotton. The smaller hook tightens the fabric so the stuffing does not show through the stitches.