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Crochet Hook Size Chart: Millimeters, US Letters and Old UK Numbers
The millimeter size is the only reliable crochet hook measurement: it is the diameter of the shaft. US hooks add a letter and number (5 mm = H-8), and old UK hooks used numbers that run backward, so a bigger UK number means a smaller hook.
Updated:
- Most-used sizes: 3.5 mm (E-4), 4 mm (G-6), 5 mm (H-8), 5.5 mm (I-9) and 6 mm (J-10).
- Beginner standard: 5 mm (H-8) hook with worsted (#4) yarn.
- Old UK numbers run in reverse: UK 8 = 4 mm, UK 6 = 5 mm, UK 4 = 6 mm.
- Letter sizes are not perfectly standard between brands, so always match the millimeter size given in the pattern.
- Amigurumi uses a hook 1–2 sizes smaller than the yarn label; blankets and drapey garments often go a size larger.
Crochet hook size conversion chart
| Millimeters | US size | Old UK size |
|---|---|---|
| 2.25 mm | B-1 | 13 |
| 2.75 mm | C-2 | – |
| 3.25 mm | D-3 | 10 |
| 3.5 mm | E-4 | 9 |
| 3.75 mm | F-5 | – |
| 4 mm | G-6 | 8 |
| 4.5 mm | 7 | 7 |
| 5 mm | H-8 | 6 |
| 5.5 mm | I-9 | 5 |
| 6 mm | J-10 | 4 |
| 6.5 mm | K-10½ | 3 |
| 8 mm | L-11 | 0 |
| 9 mm | M/N-13 | 00 |
| 10 mm | N/P-15 | 000 |
| 15 mm | P/Q | – |
| 19 mm | S | – |
A dash means there is no common equivalent. Modern UK and European patterns give sizes in millimeters, which avoids confusion.
How to choose the right hook size
- Start with the yarn label. Most labels print a recommended hook size or a small grid with a hook symbol and a millimeter number.
- Then check the pattern. If the pattern names a hook, use that size for your gauge swatch.
- Adjust for the project. Go smaller for dense, firm fabric (amigurumi, bags, baskets). Go larger for soft drape (shawls, cardigans, lacy blankets).
- Adjust for your tension. Tight crocheters often need a hook one size larger than the pattern; loose crocheters one size smaller. A gauge swatch tells you which.
Hook size by yarn weight
| Yarn weight | Typical hook range |
|---|---|
| Lace (#0) | Steel hooks or 1.5–2.25 mm |
| Super fine / fingering (#1) | 2.25–3.5 mm (B-1 to E-4) |
| Fine / sport (#2) | 3.5–4.5 mm (E-4 to 7) |
| Light / DK (#3) | 4.5–5.5 mm (7 to I-9) |
| Medium / worsted, aran (#4) | 5.5–6.5 mm (I-9 to K-10½) |
| Bulky / chunky (#5) | 6.5–9 mm (K-10½ to M/N-13) |
| Super bulky (#6) | 9–15 mm (M/N-13 to P/Q) |
| Jumbo (#7) | 15 mm and larger |
These are the standard guideline ranges. In practice many crocheters use 5 mm with worsted yarn, slightly below the range, for a firmer fabric.
Hook types: inline vs tapered, and materials
- Inline hooks have a straight throat that is the same width as the shaft, with a deep, pointed head. Many people find stitches come out very even.
- Tapered hooks have a rounded head and a throat that narrows. They glide quickly through stitches and many beginners find them comfortable.
- Ergonomic handles add a thicker grip that reduces strain on long sessions.
- Materials: aluminum is smooth and fast; bamboo and wood are warm and grip slippery yarn better; plastic is light and common in big sizes; steel is used for very small hooks and thread crochet.
Neither style is better; it comes down to how your hand moves. If your wrist hurts, try a different style or handle before giving up.
Hook size for common projects
| Project | Typical yarn | Typical hook | Why |
|---|---|---|---|
| Amigurumi | DK or worsted | 2.5–4 mm | tight stitches hide the stuffing |
| Dishcloths, coasters | worsted cotton | 4–5 mm | firm, absorbent fabric |
| Hats and beanies | worsted | 5–5.5 mm | warm but still stretchy |
| Blankets | worsted or chunky | 5–9 mm | soft drape, works up fast |
| Sweaters and cardigans | DK or worsted | 4.5–6 mm | drape matters more than density |
| Shawls and lace | fingering or lace | 3.5–5 mm | a larger hook opens up the lace |
| Baskets and rugs | bulky or cord | 6–10 mm | stiff fabric that holds its shape |
Treat these as starting points. The fabric you want matters more than the number on the hook: if a swatch feels stiff like cardboard, go up a size; if you can see through it when you did not mean to, go down.
A common trick is to use a hook one or two sizes larger for the foundation chain only. Tight foundation chains are the main reason the bottom edge of a blanket or scarf pulls in narrower than the rest.
Steel hooks for thread crochet
Thread crochet (doilies, lace edgings, fine jewelry) uses steel hooks under about 2 mm. Steel hook numbers follow their own system where a higher number means a thinner hook. Because the numbering differs by country and brand, buy and follow steel hooks by their millimeter size too.
Yarny's stitch (gauge) calculator helps you check whether your hook and yarn match a pattern, and every Yarny pattern lists the materials it uses.
Frequently asked questions
What size crochet hook is best for beginners?
A 5 mm (US H-8) hook with worsted-weight yarn. It is large enough to see and count the stitches, small enough to make a neat fabric, and matches many beginner patterns.
Is a 5 mm crochet hook the same as H-8?
Yes. 5 mm is labeled H-8 in standard US sizing. Letter labels can vary slightly between brands and older hooks, which is why the millimeter size printed on the hook is the one to trust.
What does the UK number on old crochet hooks mean?
Older British hooks were numbered in reverse, so a larger number means a smaller hook. For example, UK 8 is 4 mm and UK 6 is 5 mm. Modern UK hooks and patterns use millimeters.
What happens if I use a different hook size than the pattern?
A larger hook makes bigger stitches, so the project comes out larger, looser and uses more yarn. A smaller hook makes it smaller and denser. For items that need to fit, make a gauge swatch and change hook size until it matches.
How do I find the size of an unmarked hook?
Use a needle and hook gauge, a flat tool with sized holes. Push the shaft, not the head, through the holes until you find the one it fits snugly. That is the millimeter size.