3.5 mm crochet hook
The short answer
A 3.5 mm hook is a US size E/4, UK 9, and 6/0号 in Japan. Buy by the millimetre number — it's printed on every hook and it means the same thing everywhere.
DK weight, granny squares.
The same hook in every system
| Millimetres (the one that always works) | 3.5 mm |
|---|---|
| US | E/4 |
| UK | 9 |
| Japanese 号 | 6/0号 |
| Type | standard |
Yarn weights that suit this hook
2 standard yarn weights list 3.5 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 3.5 mm you will land toward the loose end. Swatch before you commit.
| US weight | UK | Japan | sc / 4 in |
|---|---|---|---|
| Super Fine | 4 ply | 合細 | 21-32 |
| Fine | 5 ply | 中細 | 16-20 |
3.5 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.