Crochet Hook Sizes Chart: US, UK and Metric
Every standard crochet hook from 2 mm to 30 mm with its US letter, old UK number and the yarn weight it suits. Select your yarn weight to highlight the right hooks.
Recommended hook for Worsted: 4.5–5.5 mm
| Metric (mm) | US Size | UK (old) | Yarn Weight |
|---|---|---|---|
| 2 mm | — | 14 | Lace weight / thread |
| 2.25 mm | B-1 | 13 | Fingering / lace weight |
| 2.5 mm | — | 12 | Fingering weight |
| 2.75 mm | C-2 | — | Fingering / sport weight |
| 3 mm | — | 11 | Sport weight |
| 3.25 mm | D-3 | 10 | Sport weight |
| 3.5 mm | E-4 | 9 | Sport / DK weight |
| 3.75 mm | F-5 | — | DK weight |
| 4 mm | G-6 | 8 | DK / light worsted |
| 4.5 mm | 7 | 7 | Worsted weight |
| 5 mm | H-8 | 6 | Worsted weight |
| 5.5 mm | I-9 | 5 | Worsted / aran weight |
| 6 mm | J-10 | 4 | Aran weight |
| 6.5 mm | K-10½ | 3 | Aran / bulky weight |
| 7 mm | — | 2 | Bulky weight |
| 8 mm | L-11 | 0 | Bulky weight |
| 9 mm | M/N-13 | 00 | Bulky weight |
| 10 mm | N/P-15 | 000 | Super bulky weight |
| 11.5 mm | P-16 | — | Super bulky weight |
| 12 mm | — | — | Super bulky weight |
| 15 mm | P/Q | — | Jumbo / super bulky |
| 16 mm | Q | — | Jumbo weight |
| 19 mm | S | — | Jumbo weight |
| 25 mm | T/U/X | — | Jumbo weight |
| 30 mm | T/X | — | Jumbo weight |
Turn a photo into a real pattern
Once you have the right hook and yarn, convert any photo into a crochet chart — with the correct stitch ratio applied automatically.
Open Crochet GeneratorUS vs Metric Crochet Hook Sizes
US hook sizes use a letter-and-number system (B-1, C-2, G-6, etc.) that doesn't correspond directly to millimeter measurements in a simple way. A G hook is 4.0mm but an H hook jumps to 5.0mm — there are gaps and inconsistencies in the letter sequence. Metric sizes are the more reliable standard: if you're buying hooks online or internationally, always check the millimeter size rather than the letter designation.
Hook sizes from different manufacturers may vary slightly even at the 'same' size. A 4.0mm hook from one brand may work slightly differently than a 4.0mm from another due to throat shape, taper, and metal vs. wood construction. If gauge is critical for a fitted garment, always swatch with the actual hook you'll be using.
Steel crochet hooks (for fine thread lace work) use a different numbering system that runs in reverse — larger numbers are smaller hooks. Steel hook sizes are not part of the lettered system: per the Craft Yarn Council they run from size 00 (2.7 mm) down to size 14 (0.9 mm), and exact millimeters vary a little by brand, so check the mm on the hook. They're used for crochet thread, doilies, and fine lace — not for standard yarn.
Choosing the Right Hook for Your Yarn
Most yarn labels show a recommended hook size range on the label. This is the starting point, not a rule — your personal tension (how tightly or loosely you crochet) affects whether you should go up or down a size. If your swatch is too small (your stitches are tighter than the pattern gauge), use a larger hook. If your swatch is too large, use a smaller hook.
The number in a US hook size matches the US knitting needle of the same diameter: an H-8 hook and a US 8 needle are both 5 mm, a G-6 hook and a US 6 needle both 4 mm. The knitting needle size chart has the full needle list, and the yarn weight chart shows which hook range each yarn weight calls for.
For colorwork patterns like graphghans and tapestry crochet, go down one hook size from the yarn label recommendation. Colorwork tends to produce looser stitches because you're not pulling yarn as tightly with each stitch, and a tighter gauge keeps the carried yarn from showing through. For amigurumi and toys, go down significantly — you want a very tight fabric so stuffing doesn't show through gaps.
Crochet Hook Size FAQ
The standard recommendation for worsted weight is 4.5–5.5 mm (US 7 to I-9). Most worsted yarn labels say 5.0 mm (H-8). For colorwork and tapestry crochet, go down to 4.5mm for a tighter fabric. For loose, drapey projects like shawls, 5.5mm works well.
US sizes use letter-number codes (B-1 through S) that don't follow a simple formula. Metric sizes are the millimeter diameter of the hook shaft. Always use metric for precision — if a pattern calls for a G-6 hook, that's 4.0mm. If buying internationally, check the mm size.
Bulky yarn typically uses 6.5–9.0 mm hooks (US K-10½ to M/N-13). Super bulky uses 9.0–15.0 mm (N/P-15 to Q). Your yarn label will show the specific recommended size.
Yes — hook size is a starting point. If your tension gauge doesn't match the pattern gauge, change hook size. One size up = looser fabric and larger stitches. One size down = tighter fabric and smaller stitches. Always swatch for fitted garments and blankets with specific size requirements.
For amigurumi, go 1–2 sizes smaller than the yarn label suggests to create a tight fabric that won't show stuffing through gaps. For worsted weight (which would normally use 5mm), use a 3.5 or 4.0mm hook. The tight gauge is intentional.
Old UK and Canadian hooks are numbered the other way round: the bigger the number, the smaller the hook. UK 8 is 4 mm (US G-6), UK 6 is 5 mm (US H-8), UK 4 is 6 mm (US J-10). UK hooks sold today are labelled in millimeters, so the numbers mostly matter when you follow a vintage pattern. The chart above lists all three side by side.
The US letter system skips several metric sizes — 2 mm, 2.5 mm, 3 mm, 7 mm and 12 mm have no standard letter, which is why they show a dash. If a pattern gives only a millimeter size, buy by millimeters; if it gives only a letter, the chart shows the matching mm.
Steel hooks are for crochet thread: doilies, filet crochet lace, edgings and fine motifs. They are numbered in reverse, from 00 (2.7 mm, the largest) to 14 (0.9 mm, the smallest). Size 10 cotton thread usually takes a steel hook of about 1.5–1.9 mm.
Related Tools and Pages
Crochet Pattern Generator
Convert any photo to a crochet chart with SC ratio correction, confetti reduction, and yarn estimates.
Yarn Weight Converter
Convert between US, UK, and metric yarn weight names and find equivalent weights.
Crochet Yarn Calculator
Calculate how much yarn you need for any crochet project by stitch type and grid size.
Crochet Blanket Size Calculator
Find finished blanket dimensions from stitch count and gauge.
Filet Crochet Pattern Generator
Blocks-and-spaces lace charts — the classic use for steel hooks and thread.
Graphghan Pattern Generator
Turn any photo into an SC graphghan crochet blanket pattern.