A 9mm crochet hook is a US M/N-13, and UK size 00. It’s a common size for super bulky weight yarn; check it by mm first, since letter labeling gets inconsistent at this end of the chart.
What is a 9mm crochet hook used for?
This size pairs with super bulky yarn most often, and the exact fabric it produces depends more on your own tension than the label on the hook. Swatch a small square before trusting any single size for a project that needs to fit.
- Yarn weight: super bulky.
- Common projects: match the weight above to garments, amigurumi, or blankets depending on the density you want.
How 9mm compares to nearby sizes
Compared to nearby sizes, a 8mm hook (L-11) produces a tighter, denser fabric in the same yarn, while a 10mm hook (N/P-15) opens the fabric up for a looser drape. Choose between them based on whether a project needs structure or drape. My rule of thumb is to size down for anything that needs to hold stuffing or structure, and size up for anything meant to drape.
Frequently asked questions
What letter is a 9mm crochet hook?
A 9mm hook is a US M/N-13. In UK and Canadian sizing, the same hook is a 00.
What yarn weight uses a 9mm hook?
Super bulky weight yarn is the usual match for a 9mm hook, though a gauge swatch is more reliable than the label on any given skein.
See the full hook size chart
Compare 9mm against every other mm, US, and UK size in one table.