Crochet Hook Sizes: The Complete Chart (mm, US and UK)
Every crochet hook size in millimetres with its US letter and UK number, which yarn weight each one suits, and how to pick a hook when a pattern gives none.
Pattern at a glance
US terms- Skill level
- Beginner
- Time
- 4 minute read
In this post
- The quick answer
- Crochet hook size conversion chart
- Yarn weights and the hooks that suit them
- When to go smaller than the label says
- Common questions
- What is the most used crochet hook size?
- What hook size is best for beginners?
- Does the hook size change my finished size?
- Are UK hook numbers the reverse of US ones?
- What hook do I use if the pattern doesn't say?
Hook sizes are written three different ways depending on where the pattern came from: millimetres (universal), a US letter-number, or a UK number that counts the opposite way. This page converts all three and tells you which hook goes with which yarn.
Millimetres are the only measurement that never changes. If a pattern gives you a letter and you're unsure, work from the mm size printed on the hook itself.
The quick answer
For worsted weight (#4) yarn — the most common yarn in US patterns — use a 5 mm (H-8) hook for blankets and garments, and a 3.5 mm (E-4) hook for amigurumi, where you want a tight fabric that stuffing can't show through.
The rest of this post is just below — free, as always.
Crochet hook size conversion chart
| Metric (mm) | US size | UK size | Typical yarn weight |
|---|---|---|---|
| 2.0 mm | — | 14 | Lace (#0) |
| 2.25 mm | B-1 | 13 | Lace / super fine (#0–1) |
| 2.75 mm | C-2 | 12 | Super fine (#1) |
| 3.25 mm | D-3 | 10 | Fine (#2) |
| 3.5 mm | E-4 | 9 | Fine (#2) · amigurumi in worsted |
| 3.75 mm | F-5 | — | Light / DK (#3) |
| 4.0 mm | G-6 | 8 | Light / DK (#3) |
| 4.5 mm | 7 | 7 | Light to medium (#3–4) |
| 5.0 mm | H-8 | 6 | Medium / worsted (#4) |
| 5.5 mm | I-9 | 5 | Medium / worsted (#4) |
| 6.0 mm | J-10 | 4 | Medium to bulky (#4–5) |
| 6.5 mm | K-10½ | 3 | Bulky (#5) |
| 8.0 mm | L-11 | 0 | Bulky (#5) |
| 9.0 mm | M/N-13 | 00 | Super bulky (#6) |
| 10.0 mm | N/P-15 | 000 | Super bulky (#6) |
| 15.0 mm | P/Q | — | Jumbo (#7) |
| 16.0 mm | Q | — | Jumbo (#7) |
| 19.0 mm | S | — | Jumbo (#7) |
Watch out for US letters above J. Manufacturers don't agree on them — one brand's "N" is 9 mm and another's is 10 mm. Buy by millimetres above 6 mm.
Yarn weights and the hooks that suit them
| Yarn weight | Also called | Usual hook |
|---|---|---|
| #0 Lace | Thread, cobweb | 1.5–2.25 mm |
| #1 Super fine | Fingering, sock, 4-ply | 2.25–3.5 mm |
| #2 Fine | Sport, baby | 3.5–4.5 mm |
| #3 Light | DK, light worsted, 8-ply | 4.5–5.5 mm |
| #4 Medium | Worsted, aran, afghan | 5.5–6.5 mm |
| #5 Bulky | Chunky, craft, rug | 6.5–9 mm |
| #6 Super bulky | Super chunky, roving | 9–15 mm |
| #7 Jumbo | Arm-knitting weight | 15 mm and up |
Those are the ranges yarn labels suggest for a normal, drapey fabric. Patterns regularly break them on purpose — see below.
When to go smaller than the label says
Three cases where a smaller hook is the right answer:
- Amigurumi. Go down one to two sizes — a 3.5 mm hook with worsted yarn. The fabric must be tight enough that fiberfill can't peek through. Our amigurumi guide explains why.
- Bags and baskets. A tighter fabric holds its shape when loaded. Our basket pattern uses a hook one size down for exactly this.
- Loose hands. If your swatch comes out bigger than the stated gauge, the fix is a smaller hook, not tighter stitching.
Common questions
What is the most used crochet hook size?
5 mm (US H-8). It pairs with worsted weight yarn, which is the most widely available yarn and the default in most American patterns.
What hook size is best for beginners?
5 mm (H-8) with a smooth worsted yarn. It's large enough to see each stitch clearly but not so large that the fabric turns gappy.
Does the hook size change my finished size?
Yes, a great deal. A hook half a millimetre larger can add several centimetres across a garment. For anything that must fit, crochet a gauge swatch and change hook size until your stitch count matches the pattern.
Are UK hook numbers the reverse of US ones?
Effectively, yes. UK numbers get smaller as the hook gets bigger (a UK 14 is 2 mm, a UK 4 is 6 mm), while US letters run A upward as the hook gets bigger. Use the chart above rather than converting in your head.
What hook do I use if the pattern doesn't say?
Use the hook printed on the yarn's own label — every ball band gives a recommended hook size and gauge.
Bookmark this page: it's the one chart you'll keep coming back to. 🪝
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YarnBloom shares cozy, beginner-friendly crochet patterns written in clear US terms, with a stitch count on every round and tips for the tricky bits. Grab your hook — let’s make something lovely.
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