Knitting needles are labeled differently in the US, metric, and old UK systems. This chart lines the three up so you can convert between patterns.
| US size | Metric (mm) | UK / old |
|---|---|---|
| 0 | 2.0 | 14 |
| 1 | 2.25 | 13 |
| 2 | 2.75 | 12 |
| 3 | 3.25 | 10 |
| 5 | 3.75 | 9 |
| 6 | 4.0 | 8 |
| 7 | 4.5 | 7 |
| 8 | 5.0 | 6 |
| 9 | 5.5 | 5 |
| 10 | 6.0 | 4 |
| 10.5 | 6.5 | 3 |
| 11 | 8.0 | 0 |
| 13 | 9.0 | 00 |
| 15 | 10.0 | 000 |
See the Needle Size Converter and the Crochet Hook Comparison.
The calculators and tools on Formula Factory are provided for general guidance and informational purposes only. Results are estimates based on standard formulas and the values you enter — they do not constitute professional engineering, electrical, or architectural advice. Always verify calculations with a qualified professional before making decisions for any safety-critical, code-compliance, or commercial application. Formula Factory makes no representations or warranties as to the accuracy or completeness of any result, and accepts no liability for errors, omissions, or any outcomes arising from reliance on this information.
