Reference
Crochet Hook Size Chart
Letters to millimeters, and the hook each yarn weight actually calls for.
By Sawyer V. · Published September 4, 2026
The short answer
For worsted weight yarn, use a 5.5 to 6.5mm hook - US I-9 to K-10.5. Most worsted yarn labels suggest 5mm (H-8) because that produces a denser fabric than the standard range, which is usually what you want for a blanket or a bag. For DK use 4.5 to 5.5mm, and for bulky 6.5 to 9mm.
There is a wrinkle worth knowing before you read the table: the standard's hook recommendation and the yarn label's hook recommendation frequently disagree, and both are right for different reasons. The standard aims at a balanced fabric at the published gauge. Yarn labels often aim a half-size smaller, at a tighter fabric that wears better. Neither is wrong - but if you follow the label and then compare against the standard, it looks like an error, and it is not.
Hook size by yarn weight
| Yarn weight | Common names | Hook (mm) | Hook (US) | Crochet gauge / 4in |
|---|---|---|---|---|
| 0 Lace | Lace, 10-count thread | Steel 1.6-1.4; regular 2.25 | Steel 6, 7, 8; regular B-1 | 32-42 dc |
| 1 Super Fine | Sock, fingering, baby | 2.25-3.5 | B-1 to E-4 | 21-32 sts |
| 2 Fine | Sport, baby | 3.5-4.5 | E-4 to 7 | 16-20 sts |
| 3 Light | DK, light worsted | 4.5-5.5 | 7 to I-9 | 12-17 sts |
| 4 Medium | Worsted, afghan, aran | 5.5-6.5 | I-9 to K-10.5 | 11-14 sts |
| 5 Bulky | Chunky, craft, rug | 6.5-9 | K-10.5 to M-13 | 8-11 sts |
| 6 Super Bulky | Super bulky, roving | 9-15 | M-13 to Q | 7-9 sts |
| 7 Jumbo | Jumbo, roving | 15 and larger | Q and larger | 6 sts and fewer |
US letter sizes to millimeters
The letter system is American and it is not a scale - the letters run alphabetically while the millimeter sizes step irregularly. Always buy on the millimeter number when you can; the letter is a nickname.
| US size | Metric (mm) | Typical yarn |
|---|---|---|
| B-1 | 2.25 | Fingering, sock |
| C-2 | 2.75 | Fingering |
| D-3 | 3.25 | Fingering to sport |
| E-4 | 3.5 | Sport, baby |
| F-5 | 3.75 | Sport to DK |
| G-6 | 4.0 | DK |
| 7 | 4.5 | DK |
| H-8 | 5.0 | DK to worsted |
| I-9 | 5.5 | Worsted |
| J-10 | 6.0 | Worsted |
| K-10.5 | 6.5 | Worsted to bulky |
| L-11 | 8.0 | Bulky |
| M/N-13 | 9.0 | Bulky to super bulky |
| N/P-15 | 10.0 | Super bulky |
| P/Q | 15.0 | Super bulky to jumbo |
| Q | 16.0 | Jumbo |
| S | 19.0 | Jumbo |
The M, N, P and Q range is where brands disagree most - the same letter can be 9mm from one maker and 10mm from another. Above L-11, buy by millimeter only.
Steel hooks are a separate scale entirely
Steel hooks are numbered, and the numbering runs backwards: a steel 14 is finer than a steel 0. They are for crochet thread, doilies and fine lace, and they do not overlap usefully with yarn work. If you have bought a hook set and found tiny numbered hooks you cannot use, that is why - and it is one reason we would not start anyone on a thread-hook set. The Clover Amour steel set is a good product for the wrong job if worsted yarn is what you own.
Going up or down a hook size on purpose
Hook size is the main tension control in crochet, and moving a half-size is a legitimate design decision rather than a mistake:
- Go down a size for amigurumi, bags and anything that must hold its shape. A tighter fabric hides stuffing and resists stretching - which is why amigurumi patterns routinely call for a 3.5 or 4mm hook with worsted yarn, well below the standard range.
- Go up a size for drape - shawls, summer tops, anything that should hang rather than stand. Going up also speeds up a blanket noticeably.
- Stay in the range for garments where the pattern gives a gauge you must match.
What size hook for a blanket
For worsted yarn, most blanket patterns land on 5.5 to 6.5mm (I-9 to K-10.5), and going a half-size up from the label is common because a blanket benefits from drape and speed rather than density. For chenille super bulky yarn like Bernat Blanket, the published recommendation is 8mm (L-11).
There is a full working-through of this, including how hook size interacts with stitch choice and how much yarn each combination eats, in what hook size for a blanket.
Buying to cover the chart
If you are buying a hook set rather than individual hooks, the sizes that matter are 3.5mm to 6.5mm. That single band covers DK, worsted and the top of sport - which is most published patterns, most yarn on the shelf, and effectively everything a new crocheter will make in the first year. Our picks are in the best crochet hooks, and the beginner-specific version is the best crochet hooks for beginners.
Questions people actually ask
What size crochet hook for worsted weight yarn?
The standard range is 5.5 to 6.5mm (I-9 to K-10.5). Most worsted yarn labels suggest 5mm (H-8), which gives a tighter fabric - both are reasonable, and the difference is density rather than correctness.
What is a 5mm crochet hook in US sizes?
5mm is US H-8. It is the single most commonly recommended hook size on American worsted yarn labels.
Why do crochet hook letters not match between brands?
Because the letter system is a naming convention, not a measurement. It is consistent up to about K-10.5 and diverges above that. Buy on the millimeter size printed on the hook.
What size hook for amigurumi?
Usually a half to a full size below the yarn's recommended hook - commonly 3.5 to 4mm with worsted yarn. The goal is a fabric tight enough that stuffing does not show through the stitches.
Are steel crochet hooks the same scale as regular hooks?
No. Steel hooks use their own numbered scale that runs in the opposite direction, and they are sized for crochet thread rather than yarn.