| Age (Weight) | Venous catheters | ||||
| French size* | Length | Wire diameter | Needle gauge | ||
| mm | inches | ||||
| Newborn (4-8 kg) | 3.0 | 5-12 cm | 0.46 | 0.018 | 21 |
| Infant [<12 months] (5-15 kg) | 3.0-4.0 | 5-12 cm | 0.46 to 0.53 | 0.018 to 0.021 | 21, 20, 18 |
| 1 to <8 years (10-30 kg) | 4.0-5.0 | 5-25 cm | 0.53 to 0.89 | 0.021 to 0.035 | 20, 18 |
| ≥8 years (25-70 kg) | 5.0-8.0 | 5-30 cm | 0.89 | 0.035 | 18, 16 |
