Loopy PandaJapanese and Korean Crochet Hook Sizes in mm
Japanese crochet hooks, and the same hooks sold in Korea as 호, use n/0 numbers that grow with thickness: 2/0 is 2.0 mm, 5/0 is 3.0 mm, 7/0 is 4.0 mm, 8/0 is 5.0 mm and 10/0 is 6.0 mm. Thicker hooks are labelled in mm. Lace hooks run the other way: No.0 is 1.75 mm and No.14 is 0.50 mm.
Japanese crochet hook sizes (かぎ針) in mm
These are the sizes in the official product tables of two large Japanese hook makers, Clover (Amure range) and Tulip (Etimo range). The “/0” is part of the name: 7/0 is read “7 go” and is one hook size, not a fraction. A dash means that maker does not sell that size, or that the US system has no letter for it.
| Japanese size | Clover (mm) | Tulip (mm) | US size (same mm) |
|---|---|---|---|
| 1/0 | — | 1.80 | — |
| 2/0 | 2.0 | 2.00 | — |
| 3/0 | 2.3 | 2.20 | — |
| 4/0 | 2.5 | 2.50 | — |
| 4.5/0 | — | 2.75 | C-2 |
| 5/0 | 3.0 | 3.00 | — |
| 5.5/0 | — | 3.25 | D-3 |
| 6/0 | 3.5 | 3.50 | E-4 |
| 6.5/0 | — | 3.75 | F-5 |
| 7/0 | 4.0 | 4.00 | G-6 |
| 7.5/0 | 4.5 | 4.50 | 7 |
| 8/0 | 5.0 | 5.00 | H-8 |
| 9/0 | 5.5 | 5.50 | I-9 |
| 10/0 | 6.0 | 6.00 | J-10 |
| 10.5/0 | — | 6.50 | K-10½ |
The two makers agree on every size except 3/0 (2.3 mm at Clover, 2.2 mm at Tulip). US letters are from the Craft Yarn Council hook table; it has no letter for 2.0, 2.2, 2.3, 2.5 or 3.0 mm. For old UK numbers, see the crochet hook size chart.
Hooks thicker than 10/0: sizes in mm
There is no Japanese /0 number above 10/0 (10.5/0 at Tulip). Thicker hooks are called jumbo hooks (ジャンボかぎ針) and are simply labelled in millimetres. Clover sells jumbo hooks of 7, 8 and 10 mm; Tulip's jumbo range goes 7, 8, 10, 12 and 15 mm. So a Japanese pattern that asks for a “7mm” or “8ミリ” hook means exactly that diameter, and a US L-11 is the same as an 8 mm jumbo hook.
Lace hooks (レース針): bigger number, thinner hook
Lace hooks are fine steel hooks for crochet thread. Their numbers work the opposite way: No.0 is the thickest and each higher number is thinner. They are written without “/0”, so No.2 (1.50 mm lace hook) and 2/0 (2.0 mm crochet hook) are different hooks.
| Lace hook | Clover (mm) | Tulip (mm) |
|---|---|---|
| No.0 | 1.75 | 1.75 |
| No.2 | 1.50 | 1.50 |
| No.4 | 1.25 | 1.25 |
| No.6 | 1.00 | 1.00 |
| No.8 | 0.90 | 0.90 |
| No.10 | 0.75 | 0.75 |
| No.12 | 0.60 | 0.60 |
| No.14 | — | 0.50 |
Do not mix these up with US steel hooks. They also get thinner as the number goes up, but the numbers mean different sizes: according to the Craft Yarn Council, a US steel No.14 is 0.9 mm, while a Japanese No.14 lace hook is 0.50 mm. Some makers add even finer hooks with their own numbers, so always read the mm.
Korean hook sizes (코바늘 호수)
Korean shops sell Japanese hooks under the same numbers, with 호 instead of 号. Wool hooks (모사용 코바늘) use the /0 numbers, and a 7/0호 hook is 4.0 mm. Listings often drop the “/0”, so “7호” in a Korean pattern or shop usually means 7/0 (4.0 mm). Lace hooks (레이스용 코바늘) use the lace numbers from the table above, 0호 to 14호.
- 모사용 vs 레이스용. The same number means a different hook in the two ranges: 2호 wool hook (2/0) is 2.0 mm, 2호 lace hook is 1.50 mm. Check which one the pattern asks for.
- Unbranded sets can differ. We found at least one unbranded hook set sold in Korea whose 8/0 hook is 6.0 mm, while Clover and Tulip make 8/0 5.0 mm. The number is only a name; the mm is the size.
- Chinese patterns and yarn labels usually give the hook in mm (钩针3.0mm). See Chinese yarn labels explained for 号 on yarn and needles.
Which Japanese size to use
Follow the hook on your yarn label or pattern and match the mm. If your pattern gives a Japanese number and your hooks are marked in mm or US letters, find the mm in the first table. For amigurumi you usually go one or two sizes smaller than the label, as explained in the hook size chart. Most hooks have the mm printed on the handle; if it has worn off, push the hook through a needle and hook gauge.
Frequently asked questions
What is a 7/0 crochet hook in mm?
4.0 mm, which is a US G-6. Clover and Tulip both make 7/0 hooks 4.0 mm.
What size is a 5/0 crochet hook?
3.0 mm. There is no US letter for exactly 3.0 mm; the nearest are D-3 (3.25 mm) and a 2.75 mm C-2.
What does 7호 mean on a Korean crochet hook?
On a wool hook (모사용), 7호 is 7/0, which is 4.0 mm. On a lace hook (레이스용), the numbers follow the lace table instead, so check the mm.
Why do lace hook numbers go backwards?
Lace hook numbers are a separate system in which a higher number means a thinner hook: No.0 is 1.75 mm and No.14 is 0.50 mm. Regular crochet hooks with /0 numbers get thicker as the number goes up.
What is the biggest Japanese crochet hook number?
10/0 (6.0 mm) at Clover and 10.5/0 (6.5 mm) at Tulip. Anything thicker is a jumbo hook labelled in mm, such as 7 mm, 8 mm or 10 mm.
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