3.75 mm crochet hook
A 3.75 mm hook is a US size F/5. Buy by the millimetre number — it's printed on every hook and it means the same thing everywhere.
DK weight, garments with drape.
The same hook in every system
| Millimetres (the one that always works) | 3.75 mm |
|---|---|
| US | F/5 |
| UK | no UK size |
| Japanese 号 | no Japanese size |
| Type | standard |
Systems with no exact match
3.75 mm has no direct equivalent in 2 of the three systems. These are the closest hooks, with the size difference spelled out — substitute at your own gauge risk.
| System | Closest hook | Actual size | Difference |
|---|---|---|---|
| UK | 9 | 3.5 mm | -0.25 mm |
| Japanese | 6/0号 | 3.5 mm | -0.25 mm |
Yarn weights that suit this hook
1 standard yarn weight list 3.75 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 3.75 mm you will land toward the tight end. Swatch before you commit.
| US weight | UK | Japan | sc / 4 in |
|---|---|---|---|
| Fine | 5 ply | 中細 | 16-20 |
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.