Crochet Hook Sizes: Complete Guide with Conversion Chart
Quick answer: The most common crochet hook for beginners is a US H/8 (5.0 mm) paired with worsted weight yarn. US crochet hooks use both letters and numbers — H/8 means letter H, number 8. The full conversion chart below covers every hook from steel size 14 (0.6 mm) to size S (19 mm). Need help picking the right hook? Try the crochet hook size calculator.
Crochet hooks have one of the most confusing naming systems in any craft. Letters, numbers, and millimeters — all referring to the same hook. And if you pick up a UK pattern, the numbers mean something completely different. I've bought the wrong hook size more times than I've run out of yarn, and that's saying something.
Here's every size you'll realistically encounter, in one chart you can bookmark and stop googling.
Complete Crochet Hook Size Chart
This chart covers standard aluminum/plastic hooks for regular yarn. Steel hooks for thread crochet are in the next section.
| US Letter/Number | Metric (mm) | UK/Canadian | Recommended Yarn Weight |
|---|---|---|---|
| B/1 | 2.25 | 13 | Lace (#0), Fingering (#1) |
| C/2 | 2.75 | 12 | Fingering (#1) |
| D/3 | 3.25 | 10 | Fingering (#1), Sport (#2) |
| E/4 | 3.5 | 9 | Sport (#2) |
| F/5 | 3.75 | — | Sport (#2), DK (#3) |
| G/6 | 4.0 | 8 | DK (#3) |
| 7 | 4.5 | 7 | DK (#3), Worsted (#4) |
| H/8 | 5.0 | 6 | Worsted (#4) |
| I/9 | 5.5 | 5 | Worsted (#4) |
| J/10 | 6.0 | 4 | Worsted (#4), Bulky (#5) |
| K/10.5 | 6.5 | 3 | Bulky (#5) |
| L/11 | 8.0 | — | Super Bulky (#6) |
| M/13 | 9.0 | — | Super Bulky (#6) |
| N/15 | 10.0 | — | Super Bulky (#6) |
| P/16 | 11.5 | — | Super Bulky (#6) |
| Q | 15.0 | — | Jumbo (#7) |
| S | 19.0 | — | Jumbo (#7) |
The US letter system goes A through S (skipping several letters). The number system goes 1 through 16 (also skipping numbers). They were invented by different manufacturers and later merged, which is why the overlap isn't clean.
Steel Crochet Hook Sizes (Thread Crochet)
Steel hooks are for fine thread crochet — doilies, lace, amigurumi with crochet thread. The numbering goes in the opposite direction from regular hooks: higher numbers mean smaller hooks.
| US Steel Size | Metric (mm) |
|---|---|
| 00 | 3.5 |
| 0 | 3.25 |
| 1 | 2.75 |
| 2 | 2.25 |
| 3 | 2.1 |
| 4 | 2.0 |
| 5 | 1.9 |
| 6 | 1.8 |
| 7 | 1.65 |
| 8 | 1.5 |
| 9 | 1.4 |
| 10 | 1.3 |
| 11 | 1.1 |
| 12 | 1.0 |
| 13 | 0.85 |
| 14 | 0.75 |
Choosing the Right Hook Size
The hook size determines your gauge, which determines whether your project comes out the right size. Here's the decision process.
If you have a pattern: Use the hook size listed in the pattern. Make a gauge swatch. If your swatch is too small (too many stitches per inch), go up one hook size. Too large, go down. Your personal tension dictates the final hook choice.
If you're winging it: Check the yarn label. Every skein shows a recommended hook size inside a small hook icon. Start there and adjust based on how the fabric feels. Too stiff and dense? Go up a size. Too loose and floppy? Go down.
If you're designing: Think about the fabric you want.
| Desired Fabric | Hook Choice |
|---|---|
| Dense, stiff (amigurumi) | 1–2 sizes smaller than label |
| Standard (garments, blankets) | Label recommendation |
| Drapey, loose (shawls, scarves) | 1–2 sizes larger than label |
| Lacy, open (doilies, lace work) | 2–3 sizes larger than label |
For help matching hook to yarn weight, see the full yarn weight guide.
Hook Materials: Which One to Buy
Like knitting needles, the material changes how the hook feels in your hand. This matters more than most people realize — if your hook fights you, you'll put the project down.
| Material | Surface | Speed | Weight | Best For |
|---|---|---|---|---|
| Aluminum | Smooth, slippery | Fast | Light | Experienced crocheters, acrylic yarn |
| Bamboo/Wood | Slightly grippy | Medium | Very light | Cotton yarn, slippery yarns |
| Plastic | Smooth | Medium | Very light | Large sizes (L+), budget sets |
| Ergonomic (rubber grip) | Varies | Varies | Medium | Long sessions, hand fatigue, arthritis |
| Steel | Very smooth | Fast | Heavy | Thread crochet only |
One material trap: plastic hooks in large sizes (Q, S) can bend under tension. If you're working with tight stitches on a big plastic hook, it flexes and fights you. Wooden or bamboo hooks in those sizes hold their shape better.
Common Hook Size Mistakes
These are the ones I see most often in crochet forums, and I've made every single one.
Confusing US and UK sizes. A UK pattern saying "4.00 mm hook" is clear. A UK pattern saying "size 8 hook" means 4.0 mm. A US pattern saying "size 8 hook" (H/8) means 5.0 mm. That's a full millimeter of difference. Always check the metric measurement.
Using the same hook for knitting and crochet. Knitting needle US 8 = 5.0 mm. Crochet hook H/8 = 5.0 mm. The metric size is the same, but a crochet hook and a knitting needle are not interchangeable tools. If a knitting pattern says "US 8," it means a knitting needle. If a crochet pattern says "H/8," it means a crochet hook. Seems obvious, but the shared number system creates real confusion for people who do both crafts.
Ignoring the hook throat shape. Hooks come in two throat styles: inline (Bates style) and tapered (Boye style). Inline hooks have a consistent diameter from head to shaft. Tapered hooks get wider below the head. Same labeled size, slightly different effective gauge. If you switch brands mid-project, check your gauge.
FAQ
What crochet hook size is best for beginners?
H/8 (5.0 mm) with worsted weight yarn. The hook is big enough to grip comfortably, the stitches are large enough to see clearly, and worsted yarn is forgiving — it doesn't split easily and comes in every color. Avoid starting with anything smaller than a G/6 (4.0 mm) or thinner than DK weight yarn.
How do I measure a crochet hook with no size marking?
Use a hook gauge — a flat card with holes labeled in millimeters. Insert the shaft (not the head) of the hook into each hole until you find a snug fit. The metric measurement is your hook size. Match it to the chart above for the US letter/number equivalent. You can also use a caliper to measure the shaft diameter directly.
Can I use a different hook size than the pattern recommends?
Yes, if you adjust for gauge. A larger hook creates a looser fabric with fewer stitches per inch. A smaller hook creates a tighter fabric with more stitches per inch. For projects where size matters (garments, amigurumi, fitted items), match the pattern gauge by adjusting your hook. For scarves and blankets, you have more flexibility.
What hook size for granny squares?
Most granny square patterns use an H/8 (5.0 mm) or I/9 (5.5 mm) with worsted weight yarn, producing squares around 6–8 inches. For tighter, smaller squares (coasters, motifs), drop to a G/6 (4.0 mm). For larger, lacier squares, go up to a J/10 (6.0 mm). The crochet blanket sizes guide has stitch counts and square layouts for full blankets.
Why does my gauge not match the pattern even with the right hook?
Your tension is personal. Some people crochet tight, others loose. The hook size on the pattern is a starting point — it gives the designer the correct gauge. If you crochet tighter than average, go up one hook size. If looser, go down. The only way to know is to swatch. It takes 10 minutes and saves 10 hours of frustration.
Next Steps
- Use the crochet hook size calculator to match your yarn to the right hook based on the gauge you need.
- Read the yarn weight guide to understand yarn weight categories and how they pair with hook sizes.
- Check the crochet blanket sizes guide for blanket dimensions, stitch counts, and yarn estimates by hook size.