Japanese Needle and Hook Size Conversions

Introduction

In Japan, as with the rest of the world, crafters typically use needles (棒針, bouhari) for knitting and hooks (かぎ針, kagibari) for crochet.

In a Japanese knit/crochet pattern, the needle/hook section is often designated with one of the following:
用具 (yougu, tools)
針 (hari, needle/hook)

Examples of needle/hook sizes:

• Straight knitting needles: 棒針5号
• Circular knitting needles: 輪針4号
• Jumbo straight knitting needles: 棒針ジャンボ8ミリ
• Crochet hook: かぎ針3/0号
• Jumbo crochet hook: かぎ針ジャンボ12ミリ or occasionally かぎ針J12ミリ
• Crochet lace/steel hook: レース針2号
• Tunisian crochet hook: アフガン針8号

In US standard sizes, a size X needle and a size X hook would be the same, e.g. a US 6 needle and a US G-6 hook are both 4.0 mm in diameter. However, this is not the case with Japanese needle and hook sizes, e.g. a JPN 6 needle = 3.9 mm, a JPN 6/0 hook = 3.5 mm, and a JPN lace 6 hook = 1.00 mm. Both needle and hook chart conversions are listed below. Japanese needle sizes do not always have an exact equivalent in standard US sizes, in which case the closest size is listed.

Knitting Needle and Tunisian Crochet Hook Sizes – Standard

JPN needle size (号)			US needle equivalent
0	2.1 mm		0	2.0 mm
1	2.4 mm		1½	2.5 mm
2	2.7 mm		2	2.75 mm
3	3.0 mm		2½	3.0 mm
4	3.3 mm		3	3.25 mm
5	3.6 mm		4 or 5	3.5 or 3.75 mm
6	3.9 mm		6	4.0 mm
7	4.2 mm		6 or 7	4.0 or 4.5 mm
8	4.5 mm		7	4.5 mm
9	4.8 mm		7 or 8	4.5 or 5.0 mm
10	5.1 mm		8	5.0 mm
11	5.4 mm		9	5.5 mm
12	5.7 mm		9 or 10	5.5 or 6.0 mm
13	6.0 mm		10	6.0 mm
14	6.3 mm		10 or 10½	6.0 or 6.5 mm
15	6.6 mm		10½	6.5 mm

Knitting Needle Sizes – Jumbo

JPN needle size (ミリ)			US needle equivalent
7	7 mm		10½	6.5 mm
8	8 mm		11	8 mm
9	9 mm		13	9 mm
10	10 mm		15	10 mm
12	12 mm		17	12.75 mm
15	15 mm		19	15 mm
20	20 mm		35	19 mm
25	25 mm		50	25 mm
30	30 mm		–

Crochet Hook Sizes – Standard

JPN standard hook size (号)			US standard hook equivalent
2/0	2.0 mm		A-0 (or 4 steel)	2.0 mm
3/0	2.3 mm		B-1 (or 2 steel)	2.25 mm
4/0	2.5 mm		B-1 or C-2	2.25 or 2.75 mm
5/0	3.0 mm		C-2 or D-3	2.75 or 3.25 mm
6/0	3.5 mm		E-4 (or 00 steel)	3.5 mm
7/0	4.0 mm		G-6	4.0 mm
7.5/0	4.5 mm		—
8/0	5.0 mm		H-8	5.0 mm
10/0	6.0 mm		J-10	6.0 mm

Crochet Hook Sizes – Jumbo

JPN jumbo hook size (ミリ)			US standard hook equivalent
7	7 mm		K-10½	6.50 mm
8	8 mm		L-11	8.00 mm
9	9 mm		M/N-13	9.00 mm
10	10 mm		N/P-15	10.00 mm
15	15 mm		P/Q or Q	15 or 16 mm
20	20 mm		S	19 mm

Crochet Hook Sizes – Lace and Steel

JPN lace hook size (号)			US steel hook equivalent
0	1.75 mm		6	1.80 mm
2	1.50 mm		8	1.50 mm
4	1.25 mm		10	1.30 mm
6	1.00 mm		12	1.00 mm
8	0.90 mm		13	0.85 mm
10	0.75 mm		14	0.75 mm
12	0.60 mm		—
14	0.50 mm		—

Edited 06-05-2011 to add straight/circular needle types, and jumbo needle and hook sizes

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