6.5 mm crochet hook

The short answer

A 6.5 mm hook is a US size K/10.5, UK 3. 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 6.5 mm. Screen scaling varies by device, so treat this as a sanity check, not a measurement.

Aran to chunky, loose drapey fabric.

The same hook in every system

Millimetres (the one that always works)	6.5 mm
US	K/10.5
UK	3
Japanese 号	no Japanese size
Type	standard

Systems with no exact match

6.5 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	10/0号	6 mm	-0.5 mm

Yarn weights that suit this hook

2 standard yarn weights list 6.5 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 6.5 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
Bulky	Chunky	極太	8-11

6.5 mm hooks

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

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Nearby sizes

6 mm 7 mm 5.5 mm 5 mm 8 mm

All hook sizes · US to Japanese hook chart

Last updated 2026-08-30.