Crochet hook size converter

Choose a hook size in the system you know and see the others, plus the yarn weights it is usually recommended for. Nothing you select leaves your browser.

Choose a size above to see the conversion.

Hook size chart

mm	US	UK/Canada
2	none	14
2.25	B-1	13
2.5	none	12
2.75	C-2	none
3	none	11
3.25	D-3	10
3.5	E-4	9
3.75	F-5	none
4	G-6	8
4.5	7	7
5	H-8	6
5.5	I-9	5
6	J-10	4
6.5	K-10½	3
7	none	2
8	L-11	0
9	M/N-13	00
10	N/P-15	000
11.5	P-16	none
15	P/Q	none
16	Q	none
19	S	none
25	T/U/X	none

"none" means no size of that kind appears on the chart. Millimetres are the only measurement that is the same everywhere; US letters and numbers and the older UK/Canadian numbers are labels.

Things to know

Go by millimetres when you can. US letters vary slightly between makers. For example, a G hook is 4.0 mm on the chart but some makers list it as 4.25 mm, and a D hook is 3.25 mm on the chart but some makers list 3.125 mm. If your pattern gives mm, use mm.
UK/Canada numbers run backwards. A larger number means a smaller hook (a 14 is the smallest, a 000 is large).
Some sizes have no match. The chart has no US letter for 2.0, 2.5, 3.0 or 7.0 mm, and no UK/Canada number for 2.75 or 3.75 mm or for the sizes above 10 mm.
The hook that matches the pattern is the one that gets the pattern's gauge. If you do not, change the size. The gauge calculator says which way.

Recommended hook by yarn weight

These are the Craft Yarn Council's guidelines for the standard yarn weights; they are starting points, not rules.

Yarn weight	Hook (mm)	US hook
#0 Lace 10-count crochet thread	2.25 mm	B-1 regular hook (or a steel hook 1.4–1.6 mm)
#1 Super Fine sock, fingering, baby	2.25 to 3.5 mm	B-1 to E-4
#2 Fine sport, baby	3.5 to 4.5 mm	E-4 to 7
#3 Light DK, light worsted	4.5 to 5.5 mm	7 to I-9
#4 Medium worsted, afghan, Aran	5.5 to 6.5 mm	I-9 to K-10½
#5 Bulky chunky, craft, rug	6.5 to 9 mm	K-10½ to M-13
#6 Super Bulky super bulky, roving	9 to 15 mm	M-13 to Q
#7 Jumbo jumbo, roving	15 mm and larger	Q and larger

Questions

Is a bigger hook always better for a looser fabric?

A larger hook makes larger stitches in the same yarn, which gives a looser, drapier fabric. Amigurumi is often worked with a smaller hook than the yarn label suggests so that stuffing does not show; the pattern says which size to use.

Which hook do our patterns use?

Each pattern page and PDF lists the hook, usually in mm with the US size. Most use a worsted (#4) yarn with a 3.5 to 5.5 mm hook; see the starter supplies page. For example, the Barnaby teddy bear ($0.99) lists its hook size on the pattern page.

Sources

These are the references the tables and ranges on this page were compared against. They are guidelines, and makers differ slightly, so your pattern's own hook and gauge always win.