French Catheter Gauge Sizes

The French catheter sizing system (Fr) is a unit of measurement used to describe the diameter of a catheter. The French size is defined by the outer diameter of the catheter in millimeters. To convert French units to metric (millimeters) and vice versa, you can use the following conversion formulas:

Conversion from French (Fr) to Millimeters (mm):

• 1 French (Fr) = 0.33 millimeters (mm)

To convert from French to millimeters, you multiply the French size by 0.33.

Conversion from Millimeters (mm) to French (Fr):

• 1 millimeter (mm) = 3 French (Fr)

To convert from millimeters to French, you multiply the millimeter value by 3.

Example Conversions:

1. 10 Fr catheter:
   • 10 Fr × 0.33 = 3.3 mm
2. 5 mm catheter:
   • 5 mm × 3 = 15 Fr

Component Supply provides a downloadable French, decimal, and metric equivalent chart as a resource.