Needle & hook sizes

What size is my needle in US and UK?

Pattern from another country? Type the needle or hook size it gives, in any system, and see what it is in the others.

Worked example

A 4 mm (US 6) needle is an old UK 8.

Knitting needle sizes
MetricUSOld UK / CanadianJapanese
1.5 mm000——
1.75 mm00——
2 mm014—
2.1 mm——0
2.25 mm113—
2.4 mm——1
2.5 mm(1½)——
2.7 mm——2
2.75 mm212—
3 mm(2½)113
3.25 mm310—
3.3 mm——4
3.5 mm4——
3.6 mm——5
3.75 mm59—
3.9 mm——6
4 mm68—
4.2 mm——7
4.5 mm778
4.8 mm——9
5 mm86—
5.1 mm——10
5.4 mm——11
5.5 mm95—
5.7 mm——12
6 mm10413
6.3 mm——14
6.5 mm10½3—
6.6 mm——15
7 mm(10¾)2—
7.5 mm—1—
8 mm110—
9 mm1300—
10 mm15000—
12 mm(17)——
12.75 mm17——
15 mm19——
16 mm(19)——
19 mm35——
20 mm(36)——
25 mm50——
30 mm———
35 mm70——
Crochet hook sizes
MetricUSJapanese
2 mm—2/0
2.25 mmB-1—
2.3 mm—3/0
2.5 mm—4/0
2.75 mmC-2—
3 mm—5/0
3.25 mmD-3—
3.5 mmE-46/0
3.75 mmF-5—
4 mmG-67/0
4.5 mm77.5/0
5 mmH-88/0
5.5 mmI-99/0
6 mmJ-1010/0
6.5 mmK-10½—
7 mm——
8 mmL-11—
9 mmM/N-13—
10 mmN/P-15—
11.5 mmP-16—
12 mm——
15 mmP/Q—
16 mmQ—
19 mmS—
25 mmT/U/X—
30 mmT/X—
Steel crochet hook sizes
MetricBoyeSusan BatesJapanese laceOld UK
0.5 mm——14—
0.6 mm——12—
0.75 mm14—107
0.85 mm13——6½
0.9 mm—148—
0.95 mm—13——
1 mm121266
1.05 mm—11——
1.1 mm11——5½
1.15 mm—10——
1.25 mm—94—
1.3 mm10——5
1.4 mm98—4
1.5 mm8723
1.6 mm—6——
1.65 mm7——2½
1.7 mm—5——
1.75 mm—40—
1.8 mm6——2
1.9 mm5——1½
2 mm4——1
2.1 mm33——
2.2 mm—2——
2.25 mm2———
2.35 mm—1——
2.5 mm———0
2.55 mm—0——
2.7 mm—00——
2.75 mm1———
3 mm———00
3.25 mm0———
3.5 mm00———
Circular needle lengths
InchescmUsed for
9 in23 cmSocks and mittens
12 in30 cmSocks and sleeves
16 in40 cmHats and neckbands
20 in50 cmCowls and baby sweaters
24 in60 cmChild sweaters and yokes
32 in80 cmSweaters, and magic loop for small rounds
40 in100 cmBig sweaters, and magic loop
47 in120 cmShawls and blankets
60 in150 cmBlankets

How it works

Metric (mm) is the needle's actual diameter, and the only system that means the same thing everywhere — when in doubt, go by mm.

US needle numbers get bigger as needles get thicker. Old UK and Canadian numbers run the other way: a UK 14 is a thin 2 mm (US 0) needle, a UK 000 is 10 mm (US 15). Some sizes simply have no equivalent in another system.

A number on its own can mean different needles: an 8 could be a 5 mm (US 8) needle or an old UK 8, which is 4 mm (US 6). If your pattern doesn't say which, the converter shows every one.

Japanese needles are their own sizes, numbered 0 to 15: a Japanese 7 sits between 4 mm (US 6) and 4.5 mm (US 7). Japanese hooks are written 7/0: a 7/0 is a 4 mm (US G-6) hook.

US crochet hooks use a letter and a number: a 5 mm (US H-8) hook, for example. Brands don't always agree on the in-between letters, so check the mm printed on the hook.

Steel hooks for thread crochet are numbered by each maker, and the same number is a different size from Boye and from Susan Bates. Go by the mm.

Some brands print a US number on needles that have no standard US size. The chart shows those in brackets.

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