What is French Scale of Urethral Toys?


Pratt Urethral Beginners Sound Kit. Sizes: 3 to 18 French (Fr)

French scale, also known as French catheter size or French gauge system is a measuring system for  urethral devices. Sometimes, the sizes of urethral toys such as penis plugs, urethral sounds or catheters are given in French scale (Fr).

This is why it is important to understand this measuring unit and to know how these sizes correspond to millimeters and inches.

French Scale Explained

French scale is not the most popular measuring system but those who want to deal with urethral toys will encounter it often. Since the diameter and thickness of urethral toys are very important for making a perfect fit, it is vital to be familiar with the French scale and to know how these units correspond with millimeters and inches.

The French scale, abbreviated as Fr, is three times the diameter of the urethral toy in millimeters. It means that you can convert any diameter size in millimeters into Fr by simply multiplying this size by 3. Similarly, you can convert a size in French scale into millimeters by dividing this size by 3.

The French size measures the external diameter of the urethral instrument such as a catheter or a urethral toy. This system was devised by Joseph-Frédéric-Benoît Charrière, a 19th century French maker of various surgical instruments.

Unlike typical gauge sizes, where the larger size has the smaller number, larger French sizes correspond to larger instruments. For example, 12 gauge is smaller than 8 gauge, but 12 Fr is larger than 8 Fr.

Using French Scale

As you can see, the French scale has a connection to the metric system but the metric and French scale are not equivalents. It means that any size in Fr will not be the same in number as the size in millimeters or inches.

This is why it is so important to pay attention to the measuring units when you want to purchase urethral toys. Do not assume that the measurement is in millimeters or in inches. Sometimes, the manufacturer will simply state that the size is, say, “10 French”. It doesn’t mean that the size is 10 millimeters. You need to use a conversion chart to see the size in millimeters.

Keep in mind that the French scale (Fr) can go for all types of urethral instruments and devices. Urethral toys, catheters or any other type of a device that gets indie of the urethra can use French scale.

Converting French Scale

It is generally not too difficult to convert a French scale into millimeters and inches, but it does require some knowledge of mathematics to do so. This is why many people use handy conversion charts or conversion tools. Also, many people know all of the three main scales (millimeters, inches and Fr) for the most common urethral sizes they use. Whatever you do, it is important to be able to convert a urethral toy size given in any scale so you know what kind of a toy you are dealing with.

Here is a quick conversion chart for some of the common French sizes:

French Scale (Fr) Diameter in mm  Diameter in 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 0.17
14 4.7 0.184
15 5 0.197
16 5.3 0.21
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
About Melina Jackson:
Melina is a staff writer, author and researcher for TheChainGang. She covers numerous subjects, from body jewelry to kinky adult toys. In addition to this, Melina also provides occasional adult toy reviews written in an interesting and sexy manner. She says: “I’m happy and proud to be a part of TheChainGang team. I enjoy every research because I know how much importance TheChainGang places on customer satisfaction and providing accurate and up to date information. I particularly like sex toy reviews: they are fun to write and experience”. In addition to writing and researching, Melina provides online research results and handy information for buyers interested in accurate and easily understandable tips and advice on choosing the best adult toys and body jewelry.

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