Crochet Hook Size Chart

US hooks are labeled with a letter and a number, which don't always move in lockstep — this table lines up the letter/number sizing against the metric millimeter size that stays consistent across every hook you own.

Metric (mm)	US Size	UK / Old Size
2.25 mm	B-1	13
2.75 mm	C-2	12
3.25 mm	D-3	10
3.5 mm	E-4	9
3.75 mm	F-5	8
4.0 mm	G-6	8
4.5 mm	7	7
5.0 mm	H-8	6
5.5 mm	I-9	5
6.0 mm	J-10	4
6.5 mm	K-10½	3
8.0 mm	L-11	0
9.0 mm	M/N-13	00
10.0 mm	N/P-15	000
15.0 mm	P/Q	—
16.0 mm	Q	—
19.0 mm	S	—

Steel hooks used for thread crochet have their own, separate size range (typically 00 down to 16, running opposite to regular hook sizing) and aren't included in this table.