| thou | 1 th | 2 th | 3 th | 4 th | 5 th | 6 th | 7 th | 8 th | 9 th | 10 th | 11 th | 12 th | 13 th | 14 th | 15 th | 16 th | 17 th | 18 th | 19 th | 20 th | 21 th | 22 th | 23 th | 24 th | 25 th | 26 th | 27 th | 28 th | 29 th | 30 th | 31 th | 32 th | 33 th | 34 th | 35 th | 36 th | 37 th | 38 th | 39 th | 40 th | 41 th | 42 th | 43 th | 44 th | 45 th | 46 th | 47 th | 48 th | 49 th | 50 th | 51 th | 52 th | 53 th | 54 th | 55 th | 56 th | 57 th | 58 th | 59 th | 60 th | 61 th | 62 th | 63 th | 64 th | 65 th | 66 th | 67 th | 68 th | 69 th | 70 th | 71 th | 72 th | 73 th | 74 th | 75 th | 76 th | 77 th | 78 th | 79 th | 80 th | 81 th | 82 th | 83 th | 84 th | 85 th | 86 th | 87 th | 88 th | 89 th | 90 th | 91 th | 92 th | 93 th | 94 th | 95 th | 96 th | 97 th | 98 th | 99 th | 100 th |
| french; charriere | 0.0762 F | 0.1524 F | 0.2286 F | 0.3048 F | 0.381 F | 0.4572 F | 0.5334 F | 0.6096 F | 0.6858 F | 0.762 F | 0.8382 F | 0.9144 F | 0.9906 F | 1.0668 F | 1.143 F | 1.2192 F | 1.2954 F | 1.3716 F | 1.4478 F | 1.524 F | 1.6002 F | 1.6764 F | 1.7526 F | 1.8288 F | 1.905 F | 1.9812 F | 2.0574 F | 2.1336 F | 2.2098 F | 2.286 F | 2.3622 F | 2.4384 F | 2.5146 F | 2.5908 F | 2.667 F | 2.7432 F | 2.8194 F | 2.8956 F | 2.9718 F | 3.048 F | 3.1242 F | 3.2004 F | 3.2766 F | 3.3528 F | 3.429 F | 3.5052 F | 3.5814 F | 3.6576 F | 3.7338 F | 3.81 F | 3.8862 F | 3.9624 F | 4.0386 F | 4.1148 F | 4.191 F | 4.2672 F | 4.3434 F | 4.4196 F | 4.4958 F | 4.572 F | 4.6482 F | 4.7244 F | 4.8006 F | 4.8768 F | 4.953 F | 5.0292 F | 5.1054 F | 5.1816 F | 5.2578 F | 5.334 F | 5.4102 F | 5.4864 F | 5.5626 F | 5.6388 F | 5.715 F | 5.7912 F | 5.8674 F | 5.9436 F | 6.0198 F | 6.096 F | 6.1722 F | 6.2484 F | 6.3246 F | 6.4008 F | 6.477 F | 6.5532 F | 6.6294 F | 6.7056 F | 6.7818 F | 6.858 F | 6.9342 F | 7.0104 F | 7.0866 F | 7.1628 F | 7.239 F | 7.3152 F | 7.3914 F | 7.4676 F | 7.5438 F | 7.62 F |
A thousandth of an inch is a derived unit of length in an inch-based system of units. Equal to 0.001 inches, it is normally referred to as a thou /ˈθaʊ/, a thousandth, or (particularly in the United States) a mil.
| 1 thous = 0.0762 french; charriere | 4 thous = 0.3048 french; charriere |
| 1.5 thous = 0.1143 french; charriere | 4.5 thous = 0.3429 french; charriere |
| 2 thous = 0.1524 french; charriere | 5 thous = 0.381 french; charriere |
| 2.5 thous = 0.1905 french; charriere | 5.5 thous = 0.4191 french; charriere |
| 3 thous = 0.2286 french; charriere | 6 thous = 0.4572 french; charriere |
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).
| 1 french; charriere = 13.123359580052 thous | 4 french; charriere = 52.49343832021 thous |
| 1.5 french; charriere = 19.685039370079 thous | 4.5 french; charriere = 59.055118110236 thous |
| 2 french; charriere = 26.246719160105 thous | 5 french; charriere = 65.616797900262 thous |
| 2.5 french; charriere = 32.808398950131 thous | 5.5 french; charriere = 72.178477690289 thous |
| 3 french; charriere = 39.370078740157 thous | 6 french; charriere = 78.740157480315 thous |
| 1 thous = 0.0762 french; charriere |
| 1 french; charriere = 13.1233596 thous |