6 mm crochet hook
The short answer
A 6 mm hook is a US size J/10, UK 4, and 10/0号 in Japan. Buy by the millimetre number — it's printed on every hook and it means the same thing everywhere.
Aran weight, fast blankets.
The same hook in every system
| Millimetres (the one that always works) | 6 mm |
|---|---|
| US | J/10 |
| UK | 4 |
| Japanese 号 | 10/0号 |
| Type | standard |
Yarn weights that suit this hook
1 standard yarn weight list 6 mm inside their recommended hook range. Expected single crochet gauge over 4 inches is shown as a range — the CYC figures assume a mid-range hook, so at 6 mm you will land toward the loose end. Swatch before you commit.
| US weight | UK | Japan | sc / 4 in |
|---|---|---|---|
| Medium | Aran | 並太 | 11-14 |
6 mm hooks
Aluminium, ergonomic and Japanese-style options in this size.
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Nearby sizes
All hook sizes · US to Japanese hook chart
Last updated 2026-08-30.