Knitting needle conversion chart

Complete knitting needle size chart for metric (mm), modern US sizes, old UK sizes, and crochet hook letters, plus a separate Japanese size chart. All values match the live converter, because both use the same internal data.

Metric to US, UK and crochet sizes

Sizes are ordered by metric diameter in millimetres. Click a metric, US, or UK size to open the converter for that exact value. Australian and European needles also use metric sizes, so knitters in Australia usually follow the mm column directly.

Metric (mm)	US size	UK old size	Crochet hook	Typical yarn weight
2 mm	0	14	—	lace / fingering
2.3 mm	1	13	B	fingering / sock
2.5 mm	1.5	—	—	fingering
2.8 mm	2	12	C	sport
3 mm	2.5	11	—	sport / DK
3.3 mm	3	10	D	DK
3.5 mm	4	—	E	DK
3.8 mm	5	9	F	DK / light worsted
4 mm	6	8	G	worsted
4.5 mm	7	7	—	worsted
5 mm	8	6	H	worsted / aran
5.5 mm	9	5	I	aran
6 mm	10	4	J	aran / bulky
6.5 mm	10.5	3	K	bulky
7 mm	—	2	—	bulky
7.5 mm	—	1	—	bulky
8 mm	11	0	L	bulky / super bulky
9 mm	13	00	—	super bulky
10 mm	15	000	—	super bulky
12 mm	17	—	—	super bulky / jumbo
12.8 mm	17	—	—	super bulky / jumbo
15 mm	19	—	—	jumbo
16 mm	19	—	—	jumbo
19 mm	35	—	—	jumbo
20 mm	36	—	—	jumbo
25 mm	50	—	—	jumbo

Japanese knitting needle sizes (JPN)

Japanese knitting patterns often quote needle sizes using the JPN numbering system. Click a metric size below to open the converter and see the closest US and UK needle sizes for that diameter.

Metric (mm)	JPN size
2.1 mm	0
2.4 mm	1
2.7 mm	2
3.0 mm	3
3.3 mm	4
3.6 mm	5
3.9 mm	6
4.2 mm	7
4.5 mm	8
4.8 mm	9
5.1 mm	10
5.4 mm	11
5.7 mm	12
6.0 mm	13
6.3 mm	14
6.6 mm	15

Different brands may round needle diameters slightly. When matching a pattern written in another sizing system, use these charts to choose the closest size, then knit a small gauge swatch and adjust up or down one needle size if your gauge is too tight or too loose.