Standing in the craft shop staring at a wall of hooks? You are not alone. Hooks are labelled in three different systems, and the same hook can have a letter, a number and a millimetre size printed on it. Here is everything you need, in one chart.
The only number that really matters: millimetres
The millimetre (mm) size is the diameter of the hook shaft, and it is the same everywhere in the world. US letters and old UK numbers are just labels for those millimetres. When a pattern and your hook disagree, always go by mm.
Crochet hook size chart
| Metric (mm) | US size | Common uses |
|---|---|---|
| 2.25 mm | B-1 | Fine cotton, small amigurumi |
| 2.75 mm | C-2 | Sock and fingering yarn |
| 3.25 mm | D-3 | Fingering and sport yarn |
| 3.5 mm | E-4 | Sport yarn, tight amigurumi |
| 3.75 mm | F-5 | Sport and DK yarn |
| 4 mm | G-6 | DK yarn |
| 4.5 mm | 7 | DK and light worsted |
| 5 mm | H-8 | Worsted (a great first hook) |
| 5.5 mm | I-9 | Worsted and aran |
| 6 mm | J-10 | Aran and chunky |
| 6.5 mm | K-10½ | Chunky yarn |
| 8 mm | L-11 | Bulky yarn |
| 9 mm | M/N-13 | Super bulky |
| 10 mm | N/P-15 | Super bulky, quick blankets |
Granny’s tip: If you are just starting, buy a 5 mm (H-8) hook and a ball of smooth, light-coloured worsted yarn. It is the easiest combination for seeing your stitches.
How to choose the right hook
- Check the yarn label. Most labels print a recommended hook size, often next to a little hook symbol.
- Follow the pattern. The pattern tells you which hook the designer used to get their gauge.
- Go smaller for amigurumi. Toys need tight stitches so the stuffing does not show, so use a hook 0.5 to 1 mm smaller than the label suggests.
- Go bigger for drape. Shawls and wraps look lovely with a slightly larger hook.
Hook materials
Aluminium hooks are smooth and inexpensive. Ergonomic hooks with soft handles are kinder to your hands during long sessions. Wooden and bamboo hooks are warm to hold and grip slippery yarn better. There is no wrong choice: try a few and see what feels like home.





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