| Gauge | Millimeters | Inches | Decimal Conversion |
| 20G | 0.8 mm | 1/32" | 0.03 |
| 18G | 1.0 mm | 5/128" | 0.04 |
| 16G | 1.3 mm | 3/64" | 0.05 |
| 14G | 1.6 mm | 1/16" | 0.06 |
| 12G | 2.0 mm | 5/64" | 0.08 |
| 10G | 2.6 mm | 3/32" | 0.10 |
| 8G | 3 mm | 1/8" | 0.12 |
| 6G | 4 mm | 5/32" | 0.16 |
| 4G | 5 mm | 3/16" | 0.20 |
| 2G | 6-6.5 mm | 1/4" | 0.26 |
| 0G | 8 mm | 1/3" | 0.32 |
| 00G | 9-10 mm | 3/8" | 0.36 |
| - | 11 mm | 7/16" | 0.44 |
| - | 12.5 mm | 1/2" | 0.50 |
| - | 14 mm | 9/16" | 0.56 |
| - | 16 mm | 5/8" | 0.62 |
| - | 19 mm | 3/4" | 0.75 |
| - | 22 mm | 7/8" | 0.87 |
| - | 25 mm | 1" | 1.00 |