Crochet Hook Size Chart: mm, US, UK & Japanese
The millimeter size is the one that counts: it is printed on almost every hook and it never changes between brands. Use this chart to turn the mm size from a pattern into US letters, old UK numbers or Japanese sizes — and back.
| Metric | US | UK (old) | Japan | Notes |
|---|---|---|---|---|
| 2.0 mm | — | 14 | 2/0 | |
| 2.25 mm | B-1 | 13 | — | |
| 2.3 mm | — | — | 3/0 | Japanese size, popular for amigurumi. |
| 2.5 mm | — | 12 | 4/0 | No standard US letter — C-2 is 2.75 mm. A favorite for amigurumi. |
| 2.75 mm | C-2 | — | — | |
| 3.0 mm | — | 11 | 5/0 | Some brands label it C/D. |
| 3.25 mm | D-3 | 10 | — | |
| 3.5 mm | E-4 | 9 | 6/0 | |
| 3.75 mm | F-5 | — | — | |
| 4.0 mm | G-6 | 8 | 7/0 | |
| 4.5 mm | 7 | 7 | 7.5/0 | |
| 5.0 mm | H-8 | 6 | 8/0 | |
| 5.5 mm | I-9 | 5 | — | |
| 6.0 mm | J-10 | 4 | 10/0 | |
| 6.5 mm | K-10½ | 3 | — | |
| 7.0 mm | — | 2 | — | |
| 8.0 mm | L-11 | 0 | — | |
| 9.0 mm | M/N-13 | 00 | — | |
| 10 mm | N/P-15 | 000 | — | |
| 12 mm | — | — | — | |
| 15 mm | P/Q | — | — | |
| 16 mm | Q | — | — | |
| 19 mm | S | — | — | |
| 25 mm | T/U/X | — | — |
US and UK sizes follow the Craft Yarn Council hook chart. Japanese sizes are the common Tulip / Clover numbering.
Which hook for amigurumi?
Amigurumi is crocheted tightly, so the hook is usually one or two sizes smaller than the yarn label says:
| Yarn weight | Hook for amigurumi |
|---|---|
| Lace (#0) | 1.0–1.75 mm (mini) |
| Fingering / Super Fine (#1) | 1.75–2.5 mm |
| Sport / Fine (#2) | 2.25–3.0 mm |
| DK / Light (#3) | 2.5–3.5 mm |
| Worsted / Medium (#4) | 3.5–4.5 mm |
| Chunky / Bulky (#5) | 4.5–6.0 mm |
| Super Bulky (#6) | 5.0–7.0 mm |
Why US letters don’t always match
Letters and numbers were never fully standardized, so two brands can print different letters on the same size. A 2.5 mm hook has no official US letter at all — you may see it sold as B, B/C or C, while the standard C-2 is actually 2.75 mm. When a pattern gives both, follow the mm size — for example 3.5 mm (US E-4).
Steel hooks for thread and mini amigurumi
Hooks under 2 mm are usually steel (1.0 mm, 1.25 mm, 1.5 mm, 1.75 mm…). Their numbers run backwards — the higher the number, the smaller the hook — and they differ between brands, so again go by the mm size. They are used with crochet thread and for tiny amigurumi.
Japanese hook sizes
Japanese hooks (Tulip, Clover Japan) use numbers like 3/0 or 4/0: 2/0 is 2.0 mm, 3/0 is 2.3 mm, 4/0 is 2.5 mm, 5/0 is 3.0 mm, 6/0 is 3.5 mm and 7/0 is 4.0 mm. The 2.3 mm and 2.5 mm sizes are especially popular for amigurumi.
Not sure which yarn to use? See the yarn weight chart.
