Crochet Hook Size Chart
A crochet hook size chart matches the metric millimeter size to the US letter and number and to the old UK and Canadian size. For example, a 5 mm hook is an H-8 in US sizing. Use the chart and converter below to find a hook by millimeters, by letter, or by yarn weight.
Crochet hook sizes: mm, US letter and old UK
Brand labels vary slightly, so match the millimeter size first. A dash means there is no standard pairing at that size. Old UK numbers came from a wire gauge that falls between metric sizes, so charts can place UK 9 and UK 12 one row apart. Looking for thread-work hooks? See the steel hook note below the questions.
| Metric | US letter / number | Old UK / Canadian | Typical use |
|---|---|---|---|
| 2.25 mm | B-1 | 13 | thread work and very fine yarn |
| 2.5 mm | - | 12 | fine thread and lace |
| 2.75 mm | C-2 | - | fine baby and sock yarn |
| 3 mm | - | 11 | sock and light baby yarn |
| 3.25 mm | D-3 | 10 | fingering and sport yarn |
| 3.5 mm | E-4 | 9 | sport yarn and light projects |
| 3.75 mm | F-5 | - | sport and light DK yarn |
| 4 mm | G-6 | 8 | DK and light worsted yarn |
| 4.5 mm | #7 | 7 | light worsted yarn |
| 5 mm | H-8 | 6 | worsted yarn, the common all-round hook |
| 5.5 mm | I-9 | 5 | worsted and aran yarn |
| 6 mm | J-10 | 4 | aran and light bulky yarn |
| 6.5 mm | K-10.5 | 3 | bulky yarn |
| 7 mm | - | 2 | bulky yarn and thick cord |
| 8 mm | L-11 | 0 | bulky and chunky yarn |
| 9 mm | M/N-13 | 00 | super bulky yarn |
| 10 mm | N/P-15 | 000 | super bulky yarn and roving |
| 11.5 mm | P-16 | - | jumbo yarn and roving |
| 12 mm | - | - | jumbo yarn and roving |
| 15 mm | P/Q | - | jumbo projects and rugs |
| 15.75 mm | Q | - | jumbo projects and rugs |
| 16 mm | Q | - | extra jumbo projects |
| 19 mm | S | - | extra jumbo projects and giant stitches |
| 25 mm | T/U/X | - | giant, arm-knit style projects |
Last reviewed October 23, 2026. Pairings are the widely published ones, rewritten in our own table.
How to choose a crochet hook size
- Read the hook size on your pattern or yarn label.
- Find that size in the chart, by millimeters or by letter.
- Crochet a swatch with the hook and yarn you plan to use.
- Go up a hook size if the swatch has too many stitches per inch, and down a size if it has too few.
Letter sizes quick list
These four letters come up most often in patterns. Always check the millimeters on your own hook.
| US size | Metric | Old UK / Canadian |
|---|---|---|
| G-6 | 4 mm | 8 |
| H-8 | 5 mm | 6 |
| J-10 | 6 mm | 4 |
| K-10.5 | 6.5 mm | 3 |
Need the matching yarn? The yarn weight chart shows the usual hook range for each weight.
Frequently asked questions
How do I know what size crochet hook to use?
Start with the hook size on your yarn label or pattern, then crochet a swatch. If your swatch has too many stitches per inch, go up a hook size. If it has too few, go down. The yarn weight lookup on this page shows the usual hook range for each weight, so you have a sensible place to start before you swatch.
What letter is a 4.00 mm crochet hook?
A 4.00 mm hook is a G in US sizing, often marked G-6. In old UK and Canadian sizing it is an 8. Letters and numbers differ slightly between hook makers, so match the millimeter size first and treat the letter as a guide. Use the converter above to check any other size.
What are the different sizes of crochet hooks?
Crochet hooks run from tiny steel hooks from about 0.75 mm, used for thread work, up to jumbo hooks of 25 mm. In between, standard hooks start at 2.25 mm (B-1), pass 6 mm (J-10), and continue through 15 mm and beyond. The chart above lists each standard size with its US letter and old UK size.
What size is an H crochet hook in mm?
An H crochet hook is 5 mm, usually written H-8 in US sizing. That puts it in the middle of the common range and makes it a typical match for medium (worsted) weight yarn. Makers can label the same 5 mm hook slightly differently, so check the millimeter size on the handle when a pattern gives only a letter.
What size are G, J and K crochet hooks in mm?
A G hook is 4 mm, a J hook is 6 mm, and a K hook is 6.5 mm (K-10.5). The letters climb with the millimeters, but not evenly: an I is 5.5 mm and an L is 8 mm. Our chart and converter list every letter beside its metric size, so you can look up any one in seconds.
Do crochet hook sizes change between brands?
The metric size is the reliable part. Letters and numbers were set by different makers over time, so a few sizes are labeled differently, such as 9 mm shown as M or N, or 15 mm shown as P or Q. When a pattern lists both a letter and millimeters, follow the millimeters, and swatch to confirm your gauge.
Steel (thread) hook note
Steel hooks are small hooks for thread work such as lace and doilies. The common series runs from 0.75 mm (size 14) to about 2.1 mm (size 3), and some makers go finer. Their numbers run backward, so a higher number means a thinner hook. Sizes here are a guide, and makers number steel hooks differently, so rely on the millimeters.
| Metric | Steel hook number |
|---|---|
| 0.75 mm | 14 |
| 0.85 mm | 13 |
| 1 mm | 12 |
| 1.1 mm | 11 |
| 1.3 mm | 10 |
| 1.4 mm | 9 |
| 1.5 mm | 8 |
| 1.65 mm | 7 |
| 1.8 mm | 6 |
| 1.9 mm | 5 |
| 2 mm | 4 |
| 2.1 mm | 3 |