Knitting Needle Size Conversion Chart for US and Metric sizes.
| U.S. Size | Metric Size |
| 0 | 2.0 mm |
| 1 | 2.25 mm |
| 1.5 | 2.5 mm |
| 2 | 2.75 mm |
| 2.5 | 3.0 mm |
| 3 | 2.35 mm |
| 4 | 3.5 mm |
| 5 | 3.75 mm |
| 6 | 4.0 mm |
| 7 | 4.5 mm |
| 8 | 5.0 mm |
| 9 | 5.5 mm |
| 10 | 6.0 mm |
| 10 1/2 | 6.5 mm |
| 11 | 8.0 mm |
| 13 | 9.0 mm |
| 15 | 10.0 mm |
| 17 | 12.0 mm |
| 19 | 16.0 mm |
My favorite place to buy online needles is Jimmy Beans Wool. They offer many varieties of knitting needles and have excellent service. They also have an Advanced Needles Search to find the perfect needle for your project!
My own personal favorite needles are ChaioGoo. Unlike most knitters, I don’t have a set of interchangeable needles. I have acquired so many knitting needles over my 50+ years of knitting, that I already have too many to feel I need to switch to a whole new system.