Crochet hook size chart

Crochet hooks are measured by the diameter of the shaft. US hooks also carry a letter, often with a number, such as H-8. The millimeter size is the exact measurement, and letters and numbers can differ between brands, so compare millimeters when in doubt.

Hook sizes: millimeters to US

Millimeters	US size
2.25 mm	B-1
2.5 mm	none
2.75 mm	C-2
3.125 mm	D
3.25 mm	D-3
3.5 mm	E-4
3.75 mm	F-5
4 mm	G-6
4.25 mm	G
4.5 mm	7
5 mm	H-8
5.25 mm	I
5.5 mm	I-9
5.75 mm	J
6 mm	J-10
6.5 mm	K-10½
7 mm	none
8 mm	L-11
9 mm	M/N-13
10 mm	N/P-15
11.5 mm	P-16
12 mm	none
15 mm	P/Q
15.75 mm	Q
16 mm	Q
19 mm	S
25 mm	T/U/X
30 mm	T/X

Things to watch

• Same letter, different size. G-6 is 4 mm, but a hook marked just G is 4.25 mm. Q covers both 15.75 mm and 16 mm.
• Sizes without a US label. 2.5 mm, 7 mm and 12 mm hooks exist but have no US letter in the chart.
• Steel hooks run the other way. Steel hooks, used with crochet thread and lace yarn, get smaller as the number goes up. They range from about #14 (0.9 mm, the smallest) to 00 (2.7 mm). The Craft Yarn Council publishes a separate steel hook chart.

To pick a hook for your yarn, start with the yarn weight chart, then adjust after you check your gauge.

Questions

What size is an H hook in mm?

An H-8 hook is 5 mm.

What size is a G hook in mm?

G-6 is 4 mm. Some hooks are labeled G without a number, and those are 4.25 mm, so check the millimeters on the hook.

What size is a K hook?

K-10½ is 6.5 mm.

Sources

• Craft Yarn Council, Hooks and Needles: millimeter and US sizes, steel hook range, and the advice to rely on millimeter sizing. Source: Craft Yarn Council's www.YarnStandards.com
• Craft Yarn Council, Standard Yarn Weight System: steel hook numbering

Related

• Yarn weight chart

  Weights 0 to 7 with typical gauge, needle sizes and hook sizes.

• Knitting needle size chart

  Every common needle size in millimeters and US numbers.

• US vs UK crochet terms

  Convert stitch names between US and UK patterns, and spot which one you have.