Choose the system
Select regular or steel hooks, then the label system you want to search.
CHARTS & CALCULATORS
Crochet hook size chart & converter
Compare metric, US and listed UK hook sizes. Keep regular yarn hooks and steel thread hooks in separate charts.
Steel numbers belong to a separate sizing system. Several manufacturers may use the same number for different diameters.
UK/Canadian values are listed reference labels, not a universal manufacturing standard. This dataset does not map steel hooks to UK labels.
Reference ready.
| Metric (mm) | US regular | UK / Canadian reference |
|---|---|---|
| 2.25 | B-1 | 13 |
| 2.5 | — | — |
| 2.75 | C-2 | 11 |
| 3.125 | D | — |
| 3.25 | D-3 | 10 |
| 3.5 | E-4 | 9 |
| 3.75 | F-5 | 8 |
| 4 | G-6 | 8 |
| 4.25 | G | — |
| 4.5 | 7 | 7 |
| 5 | H-8 | 6 |
| 5.25 | I | — |
| 5.5 | I-9 | 5 |
| 5.75 | J | — |
| 6 | J-10 | 4 |
| 6.5 | K-10½ | 3 |
| 7 | — | — |
| 8 | L-11 | — |
| 9 | M/N-13 | — |
| 10 | N/P-15 | — |
| 11.5 | P-16 | — |
| 12 | — | — |
| 15 | P/Q | — |
| 15.75 | Q | — |
| 16 | Q | — |
| 19 | S | — |
| 25 | T/U/X | — |
| 30 | T/X | — |
References checked September 24, 2026. CYC regular hook sizes CYC steel hook sizes WEBS / Yarn.com UK reference
Check the tool and yarn labels, then match your pattern with a swatch.
CHARTS & CALCULATORS / THE USEFUL DETAILS
Start with the marking on your hook.
Compare exact matches
Enter a size and inspect all matching metric diameters. A missing label stays unlisted.
Keep a reference
Clear the query for the full chart or download only the results you need.
Frequently asked questions
Why does one US label show several millimeter sizes?
Letter and number labels can vary by maker. The query returns every exact reference match, so a letter such as G can show more than one diameter. Use the mm marking to make the final choice.
Are steel hooks the same as regular hooks?
No. A US steel number belongs to a separate system. Select the hook type before searching; never substitute a regular hook using only a steel number.
What does an empty UK entry mean?
There is no UK/Canadian equivalent listed in the reference used here. It does not mean zero, and the tool will not invent a conversion. Historical labels vary.
Does the converter choose the nearest size?
No. Millimeter queries use exact matches. If the chart has no entry for your measurement, the result stays empty instead of silently rounding to another size.
Can I substitute a hook with the same label?
Check its metric diameter, then test it with the yarn and stitch in your pattern. A label match alone cannot guarantee the same fabric.
What is included in the downloads?
CSV and PDF include the currently filtered rows and identify the hook type. PDF also includes the reference sources; clear the search to export the full selected chart.