French catheter scale chart

The French catheter scale or "French units" (F) is commonly used to measure the outside diameter of needles, catheters, and other cylindrical medical instruments. The French catheter scale (most correctly abbreviated as Fr but also often abbreviated as FR or F is commonly used to measure the outer diameter of cylindrical medical instruments Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the A hypodermic needle is a hollow needle commonly used with a Syringe to inject substances into the body In Medicine a catheter is a tube that can be inserted into a body cavity duct or vessel

1 F is equivalent to 0. 33 mm = . 013" = 1/77" of diameter. Thus the size in French units is roughly equal to the circumference of the catheter in millimetres.

French Gauge	Diameter (mm)	Diameter (inches)
3	1	0. 039
4	1. 35	0. 053
5	1. 67	0. 066
6	2	0. 079
7	2. 3	0. 092
8	2. 7	0. 105
9	3	0. 118
10	3. 3	0. 131
11	3. 7	0. 144
12	4	0. 158
13	4. 3	0. 170
14	4. 7	0. 184
15	5	0. 197
16	5. 3	0. 210
17	5. 7	0. 223
18	6	0. 236
19	6. 3	0. 249
20	6. 7	0. 263
22	7. 3	0. 288
24	8	0. 315
26	8. 7	0. 341
28	9. 3	0. 367
30	10	0. 393
32	10. 7	0. 419
34	11. 3	0. 445

References

This chart taken from Texloc

References

See also