3.25 mm crochet hook

The short answer

A 3.25 mm hook is a US size D/3, UK 10. Buy by the millimetre number — it's printed on every hook and it means the same thing everywhere.

Shaft widths drawn at roughly life size. Hold your hook against the screen — the highlighted bar is 3.25 mm. Screen scaling varies by device, so treat this as a sanity check, not a measurement.

Sport weight, baby garments.

The same hook in every system

Millimetres (the one that always works)	3.25 mm
US	D/3
UK	10
Japanese 号	no Japanese size
Type	standard

Systems with no exact match

3.25 mm has no direct equivalent in 1 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
Japanese	5/0号	3 mm	-0.25 mm

Yarn weights that suit this hook

1 standard yarn weight list 3.25 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 3.25 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

3.25 mm hooks

Aluminium, ergonomic and Japanese-style options in this size.

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Nearby sizes

3 mm 3.5 mm 2.75 mm 3.75 mm 2.5 mm

All hook sizes · US to Japanese hook chart

Last updated 2026-08-30.