Crochet Hook Sizes Chart: How to Choose the Right Hook (mm, US & UK)
CROCHET BASICS · TOOLS
🪡 Crochet Hook Sizes Chart
How to choose the right hook for your yarn, your project and your hands
Walk into any yarn shop and you will see crochet hooks labelled with letters, numbers and millimetres — sometimes all three on the same hook. It is confusing, and choosing the wrong size is one of the most common reasons a project turns out stiff, floppy or the wrong size. This guide gives you a clear crochet hook size chart, explains the different sizing systems, and shows you exactly how to pick the right hook for your yarn and your project.
Why Hook Size Matters So Much
The diameter of the hook’s shaft decides how big each loop is — and therefore how big each stitch is. A larger hook with the same yarn makes looser, drapier fabric; a smaller hook makes tighter, firmer fabric. That one choice changes:
- The finished size of your project (very important for wearables).
- The feel of the fabric: soft and drapey or dense and structured.
- How much yarn you use — looser stitches use more yarn.
- How easy it is to work: a hook that is too small for the yarn splits the strands and slows you down.
For example, for the letter keychains on this blog I deliberately use a hook a little smaller than the yarn label suggests, because a keychain needs to be firm and hold its shape. For the flower curtains, a standard hook gives the flowers enough softness to hang beautifully.
Crochet Hook Size Chart (mm, US and UK)
Millimetres are the most reliable measurement because they describe the real diameter of the shaft. US letters and old UK numbers vary slightly between brands, so when in doubt, always go by the millimetre size.
| Millimetres | US size | Old UK / Canadian |
|---|---|---|
| 2.25 mm | B-1 | 13 |
| 2.75 mm | C-2 | 12 |
| 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 |
📏 Good to know
Hooks smaller than about 2 mm are usually steel hooks, used with crochet thread for doilies and fine lace. Steel hooks have their own numbering, where a bigger number means a smaller hook — the opposite of aluminium hooks.
Matching Your Hook to Your Yarn Weight
Every yarn has a “weight” — its thickness — usually shown on the label as a number from 0 to 7. The Craft Yarn Council publishes recommended hook ranges for each weight. This is the starting point I use:
| Yarn weight | Common names | Suggested hook |
|---|---|---|
| 0 – Lace | Crochet thread, lace | Steel hooks – 2.25 mm |
| 1 – Super fine | Fingering, sock | 2.25 – 3.5 mm |
| 2 – Fine | Sport, baby | 3.5 – 4.5 mm |
| 3 – Light | DK, light worsted | 4.5 – 5.5 mm |
| 4 – Medium | Worsted, aran | 5.5 – 6.5 mm |
| 5 – Bulky | Chunky | 6.5 – 9 mm |
| 6 – Super bulky | Super chunky, roving | 9 – 15 mm |
| 7 – Jumbo | Jumbo, arm-knitting yarn | 15 mm and up |
The yarn label is your best friend: most labels show a small hook symbol with the recommended size. Start there, then adjust to your project and your own tension.
When to Go Up or Down a Hook Size
Go down 0.5–1 mm when…
- You are making amigurumi, keychains or baskets that must be firm and stuffing must not show through.
- Your stitches look loose or holey compared to the photos in the pattern.
- Your gauge swatch is bigger than the pattern’s gauge.
Go up 0.5–1 mm when…
- You want drape: shawls, summer tops, lacy curtains.
- You crochet tightly and find it hard to insert the hook.
- Your gauge swatch is smaller than the pattern’s gauge.
- You are working the foundation chain — many crocheters chain with a hook one size bigger so the first row isn’t tight.
Hook Materials: Which One Should You Choose?
| Material | Pros | Best for |
|---|---|---|
| Aluminium | Smooth, fast, affordable, very common | Most yarns, beginners |
| Ergonomic (rubber/soft handle) | Comfortable for long sessions, less hand strain | Anyone crocheting daily |
| Bamboo / wood | Warm, light, a little “grip” | Slippery yarns like silk or bamboo |
| Plastic | Light, available in large sizes | Bulky and jumbo yarn |
| Steel | Very fine and strong | Crochet thread, lace, doilies |
If you crochet more than an hour a day, an ergonomic handle is worth it. Your wrists and fingers will thank you.
Inline vs. Tapered Hooks
Look closely at the head of two hooks and you will notice a difference:
- Inline hooks have a head that is the same width as the shaft and a deep throat. Many people find they make very even stitches and grab the yarn securely.
- Tapered hooks have a rounder head that is slightly wider than the throat, which slides in and out of stitches smoothly.
Neither is better. Try one of each in your favourite size and keep whichever feels natural — your stitches will tell you.
How to Read a Hook With No Label
Old or unbranded hooks often have no size printed on them. Use a needle and hook gauge — a small card with holes of known sizes. Slide the shaft (not the head) into the smallest hole it fits through comfortably. That hole is your size in millimetres.
Building a Starter Hook Set
You do not need every size. For most home décor and gift projects, these five hooks cover nearly everything:
- 3.5 mm – fine cotton, small flowers and appliqués
- 4 mm – DK and cotton keychains, firm small pieces
- 5 mm – the all-rounder for worsted yarn
- 6 mm – blankets and softer fabric
- 8 mm – chunky yarn and quick projects
💡 My tip
Write the hook size you used on a small tag and pin it to your finished piece or your notebook. When someone asks you to make “the same one again”, you will know exactly how you made it.
🧶 Recommended hooks
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- Ergonomic crochet hook set – all common sizes with comfortable handles
- Steel crochet hook set – for thread and very fine yarn
- Hook size gauge – check the size of unmarked hooks
- Hook case – keep every size together
Frequently Asked Questions
What is the most common crochet hook size?
The 5 mm (H-8) hook is the most widely used, because it pairs with medium/worsted yarn — the most popular yarn weight.
Does the hook size in a pattern have to be exact?
No. The pattern lists the size the designer used. What matters is matching the gauge. If your stitches come out larger or smaller, change hook size until they match.
Are US and UK hook sizes the same?
Millimetre sizes are universal. Letter sizes (US) and number sizes (old UK) are different systems, so always check the millimetres when using patterns from another country.
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Written by Cozy Stitch Haven
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