4.5 mm crochet hook
The short answer
A 4.5 mm hook is a US size 7, UK 7, and 7.5/0号 in Japan. Buy by the millimetre number — it's printed on every hook and it means the same thing everywhere.
Worsted weight, blankets.
The same hook in every system
| Millimetres (the one that always works) | 4.5 mm |
|---|---|
| US | 7 |
| UK | 7 |
| Japanese 号 | 7.5/0号 unverified |
| Type | standard |
Yarn weights that suit this hook
2 standard yarn weights list 4.5 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 4.5 mm you will land toward the loose end. Swatch before you commit.
4.5 mm hooks
Aluminium, ergonomic and Japanese-style options in this size.
View on Amazon USShopping elsewhere? Amazon UAE
As an Amazon Associate we earn from qualifying purchases. Links to Amazon on this page are affiliate links; buying through them costs you nothing extra.
Nearby sizes
All hook sizes · US to Japanese hook chart
Last updated 2026-08-30.