French catheter scale

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, FR or F. It may also be abbreviated as CH or Ch (for Charrière, its inventor). However, simply gauge, G or GA generally refers to Birmingham gauge. The French size is three times the diameter in millimeters. Thus, the French size is roughly equivalent to the circumference of a circular catheter; the true circumference being slightly larger (circumference = diameter * π where π is approximately 3.14). 1 mm = 3 FrFr = 1/3 mm

French catheter scale

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, FR or F. It may also be abbreviated as CH or Ch (for Charrière, its inventor). However, simply gauge, G or GA generally refers to Birmingham gauge. The French size is three times the diameter in millimeters. Thus, the French size is roughly equivalent to the circumference of a circular catheter; the true circumference being slightly larger (circumference = diameter * π where π is approximately 3.14). 1 mm = 3 FrFr = 1/3 mm