Crochet Hook Size Conversion Chart
US, UK, metric and Japanese crochet hook sizes in one chart — find the right hook for any pattern from any country.
Patterns from different countries use different hook numbering, and a US G is not a UK G. This chart converts US letter/number, UK number, metric millimetres and common Japanese sizes, so you can follow any pattern without buying the wrong hook.
Quick-Reference Table
The full data from this cheat sheet, right on the page.
| Metric (mm) | US | UK | Japanese (approx.) |
|---|---|---|---|
| 2.00 mm | B / 1 | 14 | — |
| 2.25 mm | B / 1* | 13 | — |
| 2.50 mm | C / 2 | 12 | — |
| 2.75 mm | C / 2* | — | — |
| 3.00 mm | D / 3 | 11 | 5/0 |
| 3.25 mm | D / 3* | 10 | — |
| 3.50 mm | E / 4 | 9 | 6/0 |
| 3.75 mm | F / 5 | — | — |
| 4.00 mm | G / 6 | 8 | 7/0 |
| 4.50 mm | 7 | 7 | 7.5/0 |
| 5.00 mm | H / 8 | 6 | 8/0 |
| 5.50 mm | I / 9 | 5 | 9/0 |
| 6.00 mm | J / 10 | 4 | 10/0 |
| 6.50 mm | K / 10.5 | 3 | 10.5/0 |
| 8.00 mm | L / 11 | 0 | 13/0 |
| 9.00 mm | M / 13 | 00 | — |
| 10.00 mm | N / 15 | 000 | — |
| 12.00 mm | O / 17 | — | — |
Printable Sheet Preview
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Download Your Free Printable Sheet
Download the printable PDF below. It is the same sheet shown in the preview above, ready to print on US Letter or A4 — open it and choose Print, with Scale set to Fit to Page.
💡 Pro Printing Tip: In your printer settings, set Scale to “Fit to Printable Area” and enable “Background Graphics” for color headers.
How to Print & Use This Chart
Print on US Letter or A4 and slip this chart into your crochet project bag or pattern binder, where it is handy when a pattern names a hook you do not recognise. Use “Save as PDF” in the print dialog for a PDF copy in Letter or A4, and consider printing it at a size that fits a binder page without shrinking the table to unreadable text. A laminated copy survives yarn, coffee and being folded into bags far better than plain paper, and many crocheters keep it with their hook roll so the conversion is always beside the hooks themselves.
Always trust the millimetre size first: if a pattern says “US G” and your hook says “4.00 mm”, you have the right hook regardless of what letter another brand prints. That matters because US and UK numbering runs in opposite directions — a UK 8 is not a US 8. Before starting a garment, make a gauge swatch with the hook and yarn you plan to use, wash and block it if the finished item will be washed, and count stitches per 10 cm; if your gauge is off, change hook size rather than forcing your tension. Keep a note on this sheet of which hook you used for your favourite yarns, and future projects will start faster, with fewer frogged rows. If a pattern gives only a letter, convert it here first, then double-check against the pattern’s gauge, not just the hook name.
Frequently Asked Questions (FAQs)
Is a US G hook the same as a UK G?▼
No. Always convert by millimetres. US and UK systems use different numbering, so the same letter can mean a different size.
What hook should I use if the pattern only gives a letter?▼
Convert the letter to millimetres on this chart, then match that mm size on your hook. Check gauge afterwards.
Why does my gauge not match even with the right hook?▼
Tension varies by person and yarn. If gauge is off, go up or down a hook size until your swatch matches, rather than changing the pattern.
Do Japanese hook numbers match US numbers?▼
No. Japanese sizes like 7/0 are a separate system — convert by millimetres on this chart.