A Guide to Catheter French Sizes

What are urinary catheters?

Urinary catheters are thin, hollow tubes inserted to the urethra to collect urine from the bladder. They help prevent a buildup of urine in the kidneys, resulting in permanent damage from kidney failure. Urinary catheters are useful for individuals who are unable to empty their bladder on their own due to surgical procedures, enlarged prostates, spina bifida, urinary incontinence or other varying medical reasons. At Patient Care Medical, we carry a variety of catheters and catheter supplies to best meet your needs.

How are the sizes of urinary catheters determined?

French Sizing

Catheter sizes range anywhere from pediatric to adult men and women. Your doctor will ultimately determine the right catheter size for you. Urinary catheter size is determined by the external diameter of the tube. The universal gauge used for determining this number is known as the “French size”. The higher the number the larger the diameter. To determine the size of a urinary catheter, simply multiply the diameter length in millimeters by 3. For example, if the catheter has a diameter of 4.7 mm, it will have an FR size of 14. 

Most catheters with funnels utilize a universal-coding system to determine the sizing. Use for reference when determining your French size.

Catheter Length

Catheter length is determined by body type with factors of age, weight and sex considered. Shorter catheter length is always recommended for optimal efficiency and speed of the process. If a patient is heavier or has a larger build, a longer catheter tube will most likely be recommended. Men also need a much longer catheter tube than women. The typical catheter lengths are as follows:

Why is the right size important?

Correct catheter sizing is critical to the self-catheterization process for a number of reasons:

  1. If the FR is too small, emptying the bladder will take a considerable amount of time. 
  2. If the FR is too big for the urethra, there will be pain during catheter insertion.
  3. A catheter size that is too large may result in mucosal irritation and localized trauma.
  4. A catheter size that is smaller than the urethra will result in leakage. 

Choosing the proper catheter size is important for your overall comfort level and efficiency during self-catheterization. Patient Care Medical wants your catheter experience to be as smooth and painless as possible. To inquire about our selection of catheter sizes, contact Patient Care Medical online or at (888) 726-5066 to speak to one of our catheter specialists.