Imperial (ID - Internal Diameter) | Metric Exact | Suggested Metric Tube |
1/8 | 3.17 mm | 3mm (ID) |
5/32 | 3.97 mm | 4mm (ID) |
3/16 | 4.76 mm | 5mm (ID) |
1/4 | 6.35 mm | 6mm (ID) |
5/16 | 7.94 mm | 8mm (ID) |
3/8 | 9.53 mm | 9mm (ID) or 10mm (ID) |
1/2 | 12.7 mm | 12mm (ID) or 13mm (ID) |
5/8 | 15.8 mm | 16mm (ID) |
3/4 | 19.05 mm | 19mm (ID) |
1 inch | 25.4 mm | 25mm (ID) |