| Metric | USA | UK & Canda |
| 3.0 mm | 00 | - |
| 2.5 mm | 0 | 00 |
| 2.0 mm | 1 | 1 |
| 1.95 mm | 2 | - |
| 1.89 mm | 3 | - |
| 1.75 mm | 4 | 2 |
| 1.7 mm | 5 | - |
| 1.6 mm | 6 | - |
| 1.5 mm | 7 | 2.5 |
| 1.25 mm | 8 | 3 |
| 1.15 mm | 9 | - |
| 1.0 mm | 10 | 4 |
| 0.8 mm | 11 | - |
| 0.75 mm | 12 | 5 |
| 0.7 mm | 13 | - |
| 0.6 mm | 14 | 6 |
| Metric | USA | UK & Canada |
| 2.0 mm | - | - |
| 2.25 mm | - | 14 |
| 2.5 mm | 1 / B | 13 |
| 2.75 mm | - | 12 |
| 3.0 mm | 2 / C | 11 |
| 3.25 mm | 3 / D | 11 |
| 3.5 mm | 4 / E | 10 |
| 3.75 mm | 5 / F | 9 |
| 4.0 mm | - | - |
| 4.25 mm | 6 / G | 8 |
| 4.5 mm | - | - |
| 4.75 mm | 7 | 7 |
| 5.0 mm | 8 / H | 6 |
| 5.5 mm | 8 / I | 5 |
| 6.0 mm | 10 / J | 4 |
| 6.5 mm | 10 1/2 / K | 3 |
| 7.0 mm | - | 2 |
| 8.0 mm | 11 / L | 0 |
| 9.0 mm | 13 / M | 00 |
| 9.5 mm | - | |
| 10.0 mm | 15 / N | 000 |
| 11.5 mm | P | |
| 12.0 mm | 17 | |
| 15.75 mm | Q | |