Definition
Charrière is a unit of measurement used to indicate the outside diameter of probes, catheters, cannulas or tubes. The terms “French gauge”, “French scale” or “French” are also used in English.
Conversion 1 Charrière = 1/3 mm
The measurement in Charrière divided by 3 corresponds to the outside diameter in millimeters. Since the circumference of a circle is calculated using the formula circumference = pi * diameter, the Charrière number of a pipe roughly corresponds to its circumference in millimeters if one uses p ˜ 3 as an approximation. For example, a tube with 8 Charrière has an outside diameter of 2.67 mm, a rough circumference of 8 mm and a precise circumference of 8.39 mm.
| French (F) | |
| Charrière (CH) | O.D. mm |
| 1 | 0,33 |
| 2 | 0,67 |
| 3 | 1,00 |
| 4 | 1,33 |
| 5 | 1,67 |
| 6 | 2,00 |
| 7 | 2,33 |
| 8 | 2,67 |
| 9 | 3,00 |
| 10 | 3,33 |
| 11 | 3,67 |
| 12 | 4,00 |
| 13 | 4,33 |
| 14 | 4,67 |
| 15 | 5,00 |
| 16 | 5,33 |
| 17 | 5,67 |
| 18 | 6,00 |
| 19 | 6,33 |
| 20 | 6,67 |
| 21 | 7,00 |
| 22 | 7,33 |
| 23 | 7,67 |
| 24 | 8,00 |
| 25 | 8,33 |
| 26 | 8,67 |
| 27 | 9,00 |
| 28 | 9,33 |
| 29 | 9,67 |
| 30 | 10,00 |
| 31 | 10,33 |
| 32 | 10,67 |
| 34 | 11,33 |
| 36 | 12,00 |
| 38 | 12,67 |
| 40 | 13,33 |
| 45 | 15,00 |
| Gauge (G) | ||
| Gauge (G) | O.D. mm | Inches |
| 35 | 0,13 | 0,005 |
| 34 | 0,18 | 0,007 |
| 33 | 0,20 | 0,008 |
| 32 | 0,23 | 0,009 |
| 31 | 0,25 | 0,010 |
| 30 | 0,30 | 0,012 |
| 29 | 0,33 | 0,013 |
| 28 | 0,36 | 0,014 |
| 27 | 0,41 | 0,016 |
| 26 | 0,46 | 0,018 |
| 25 | 0,51 | 0,020 |
| 0,53 | 0,021 | |
| 24 | 0,56 | 0,022 |
| 23 | 0,64 | 0,025 |
| 22 | 0,71 | 0,028 |
| 21 | 0,81 | 0,032 |
| 20 | 0,89 | 0,035 |
| 0,97 | 0,038 | |
| 19 | 1,07 | 0,042 |
| 18 | 1,27 | 0,050 |
| 17 | 1,50 | 0,059 |
| 16 | 1,65 | 0,065 |
| 15 | 1,83 | 0,072 |
| 14 | 2,11 | 0,083 |
| 13 | 2,41 | 0,095 |
| 12 | 2,77 | 0,109 |
| 11 | 3,05 | 0,120 |
| 10 | 3,40 | 0,134 |
| 9 | 3,76 | 0,148 |
| 8 | 4,19 | 0,165 |
| 7 | 4,57 | 0,180 |
| 6 | 5,16 | 0,203 |