9 mm crochet hook

The short answer

A 9 mm hook is a US size M/13, UK 00. 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 9 mm. Screen scaling varies by device, so treat this as a sanity check, not a measurement.

Super bulky, arm-warmer weight fabric.

The same hook in every system

Millimetres (the one that always works)	9 mm
US	M/13
UK	00
Japanese 号	no Japanese size
Type	jumbo

Systems with no exact match

9 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	8mm	8 mm	-1 mm

Yarn weights that suit this hook

2 standard yarn weights list 9 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 9 mm you will land toward the loose end. Swatch before you commit.

US weight	UK	Japan	sc / 4 in
Bulky	Chunky	極太	8-11
Super Bulky	Super Chunky	超極太	6-9

9 mm hooks

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

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Nearby sizes

8 mm 10 mm 7 mm 6.5 mm 6 mm

All hook sizes · US to Japanese hook chart

Last updated 2026-08-30.