| french; charriere | 1 F | 2 F | 3 F | 4 F | 5 F | 6 F | 7 F | 8 F | 9 F | 10 F | 11 F | 12 F | 13 F | 14 F | 15 F | 16 F | 17 F | 18 F | 19 F | 20 F | 21 F | 22 F | 23 F | 24 F | 25 F | 26 F | 27 F | 28 F | 29 F | 30 F | 31 F | 32 F | 33 F | 34 F | 35 F | 36 F | 37 F | 38 F | 39 F | 40 F | 41 F | 42 F | 43 F | 44 F | 45 F | 46 F | 47 F | 48 F | 49 F | 50 F | 51 F | 52 F | 53 F | 54 F | 55 F | 56 F | 57 F | 58 F | 59 F | 60 F | 61 F | 62 F | 63 F | 64 F | 65 F | 66 F | 67 F | 68 F | 69 F | 70 F | 71 F | 72 F | 73 F | 74 F | 75 F | 76 F | 77 F | 78 F | 79 F | 80 F | 81 F | 82 F | 83 F | 84 F | 85 F | 86 F | 87 F | 88 F | 89 F | 90 F | 91 F | 92 F | 93 F | 94 F | 95 F | 96 F | 97 F | 98 F | 99 F | 100 F |
| metric inch | 0.8333333 in (metric) | 1.6666667 in (metric) | 2.5 in (metric) | 3.3333333 in (metric) | 4.1666667 in (metric) | 5 in (metric) | 5.8333333 in (metric) | 6.6666667 in (metric) | 7.5 in (metric) | 8.3333333 in (metric) | 9.1666667 in (metric) | 10 in (metric) | 10.8333333 in (metric) | 11.6666667 in (metric) | 12.5 in (metric) | 13.3333333 in (metric) | 14.1666667 in (metric) | 15 in (metric) | 15.8333333 in (metric) | 16.6666667 in (metric) | 17.5 in (metric) | 18.3333333 in (metric) | 19.1666667 in (metric) | 20 in (metric) | 20.8333333 in (metric) | 21.6666667 in (metric) | 22.5 in (metric) | 23.3333333 in (metric) | 24.1666667 in (metric) | 25 in (metric) | 25.8333333 in (metric) | 26.6666667 in (metric) | 27.5 in (metric) | 28.3333333 in (metric) | 29.1666667 in (metric) | 30 in (metric) | 30.8333333 in (metric) | 31.6666667 in (metric) | 32.5 in (metric) | 33.3333333 in (metric) | 34.1666667 in (metric) | 35 in (metric) | 35.8333333 in (metric) | 36.6666667 in (metric) | 37.5 in (metric) | 38.3333333 in (metric) | 39.1666667 in (metric) | 40 in (metric) | 40.8333333 in (metric) | 41.6666667 in (metric) | 42.5 in (metric) | 43.3333333 in (metric) | 44.1666667 in (metric) | 45 in (metric) | 45.8333333 in (metric) | 46.6666667 in (metric) | 47.5 in (metric) | 48.3333333 in (metric) | 49.1666667 in (metric) | 50 in (metric) | 50.8333333 in (metric) | 51.6666667 in (metric) | 52.5 in (metric) | 53.3333333 in (metric) | 54.1666667 in (metric) | 55 in (metric) | 55.8333333 in (metric) | 56.6666667 in (metric) | 57.5 in (metric) | 58.3333333 in (metric) | 59.1666667 in (metric) | 60 in (metric) | 60.8333333 in (metric) | 61.6666667 in (metric) | 62.5 in (metric) | 63.3333333 in (metric) | 64.1666667 in (metric) | 65 in (metric) | 65.8333333 in (metric) | 66.6666667 in (metric) | 67.5 in (metric) | 68.3333333 in (metric) | 69.1666667 in (metric) | 70 in (metric) | 70.8333333 in (metric) | 71.6666667 in (metric) | 72.5 in (metric) | 73.3333333 in (metric) | 74.1666667 in (metric) | 75 in (metric) | 75.8333333 in (metric) | 76.6666667 in (metric) | 77.5 in (metric) | 78.3333333 in (metric) | 79.1666667 in (metric) | 80 in (metric) | 80.8333333 in (metric) | 81.6666667 in (metric) | 82.5 in (metric) | 83.3333333 in (metric) |
The French scale or French gauge system is commonly used to measure the size of a catheter. It is most often abbreviated as Fr, but can often be seen abbreviated as Fg, Ga, FR or F. It may also be abbreviated as CH or Ch (for Charrière, its inventor).
| Name of unit | Symbol | Definition | Relation to SI units | Unit System |
|---|---|---|---|---|
| french; charriere | F | ≡ 1⁄3 mm | = 0.3×10−3 m | Other (Length) |
| french; charriere | metric inches | french; charriere | metric inches |
|---|---|---|---|
| 1 | = 0.83333333333333 | 4 | = 3.3333333333333 |
| 1.5 | = 1.25 | 4.5 | = 3.75 |
| 2 | = 1.6666666666667 | 5 | = 4.1666666666667 |
| 2.5 | = 2.0833333333333 | 5.5 | = 4.5833333333333 |
| 3 | = 2.5 | 6 | = 5 |
A metric inch is a nickname for a preferred 1⁄4 subdivision of an ISO 2848 basic module, or 1⁄12 of a metric foot measuring 25 millimetres (0.984 in). A metric inch is 0.4 millimetres (0.016 in) shorter than an inch.
The term was similarly used to refer to the historical Soviet Bloc practice of spacing integrated circuit pins at 1⁄10 of a 25 mm "metric inch" length, instead of the western practice of 1⁄10 of an imperial inch.
| Name of unit | Symbol | Definition | Relation to SI units | Unit System |
|---|---|---|---|---|
| metric inch | in (metric) | = 0.016 in | = 0.0004 m | Metric system SI |
| metric inches | french; charriere | metric inches | french; charriere |
|---|---|---|---|
| 1 | = 1.2 | 4 | = 4.8 |
| 1.5 | = 1.8 | 4.5 | = 5.4 |
| 2 | = 2.4 | 5 | = 6 |
| 2.5 | = 3 | 5.5 | = 6.6 |
| 3 | = 3.6 | 6 | = 7.2 |
| french; charriere | metric inches |
|---|---|
| 1 | = 0.8333333 |
| 1.2 | = 1 |
| Symbol | Definition |
|---|---|
| ≡ | exactly equal |
| ≈ | approximately equal to |
| = | equal to |
| digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |