There is much confusion about the gauges of tennis strings as well as current conventions. This blog entry seeks to clarify the standards used at Guts and Glory Tennis while providing a general overview of current status.

First off, the gauge of a tennis string refers to the diameter or thickness of the string. There are two main methods that tennis string thickness is communicated in the USA. The first is by a whole number. In tennis terms, the lower the number the thicker the gauge. The most commonly used gauges are 15, 16, 17 and 18 with 15 being the thickest and 18 being the thinnest. Because we Americas like to make things complicated and convoluted, we have added the letter “L” beside many of the gauges. Of course the “L” stands for “Light.” In our world a 15L is thinner or “lighter” than a 15 gauge, but not quite as thin as a 16. Likewise a 16L is thinner than a 16 but not quite as thin as a 17 and so forth.

The second method is what I will describe as “European” primarily because it makes use of the metric system…a system of measurements that has terrorized some Americans from childhood. Using this convention string gauges are given exact measurements using a unit called millimeters, (mm). While I find this method preferable, I do understand and appreciate that non-string geeks unfamiliar with the metric units may become even more confused by these measurements than the whole 15, 15L, 16…thing. Afterall, most Americans have an inkling of what 1/16th of an inch is, but what the heck is 1.23mm?

Many years ago when tennis was a prominent part of the Sports Supershow in the USA, representatives from professional tennis associations such as the USRSA and major manufacturers would gather to share knowledge and resources. In one of the meetings an agenda item existed that seemed to make a lot of sense. It was proposed that a standard be established to make sure all strings labeled a certain gauge would fall within a parameter of millimeters. In other words all 16ga strings fall in the range of say 1.28mm – 1.33mm. Seems to make perfect sense, doesn’t it?

Unfortunately some of the manufacturers would not agree on the parameters. (The big “G” among others, I am told.) At the time they were producing strings that did not fall into the proposed categories where they wanted them to fall. It was believed that the gauge standardization had the potential to harm sales and thus the concept was harshly rebuked. Manufacturers essentially decided to stick with their non-uniform naming conventions even if it was not consistent within their own product lines. Absolute zaniness if you ask us. The lack of ability to come to consensus has created a great deal of confusion when it comes to the average tennis player being able to understand the difference between gauges.

Today it is not uncommon to find strings with just a gauge indicated on the packaging. It may say 17ga, but what does that really mean? Because there is no universally agreed upon standard, it means the manufacturer wants to label it a 17ga. It usually falls into a broad range of diameters that can vary widely. While one company may call a 1.18mm string 18 ga, another may call it 17L while a third may even call it 17. It’s like the wild, wild west..lawless and chaotic.

The USRSA has attempted to publish a broad standard, but in reality it is not universally accepted and does little to reign in the lawlessness. (See chart at bottom of page.) The range is simply too broad with overlapping measurements to reflect the current desires of the manufacturers to whom many believe the USRSA caters. In reality it is time for it to be tightened up. It is too loosey-goosey and has no real meaning. Thus we propose a convention that we believe reflects the interests of the TENNIS PLAYER, not the manufacturer who is afraid of having a number associated with the real diameter of the string. Below is our totally awesome gauge naming convention. We hope you use it and enjoy. We believe it should become the standard. No messy overlap here. Just hardcore, label it as it is stuff that is not driven by the special/selfish interests of the major string manufacturers.

The Official Guts and Glory Tennis String Gauge Guide!

1.34mm – 1.40mm – 15L
1.33mm – 1.29mm – 16
1.28mm – 1.26mm – 16L
1.25mm – 1.23mm– 17
1.22mm – 1.19mm – 17L
1.18mm – 1.13mm – 18
1.12mm – 1.08mm – 18L
1.07mm -1.02mm – 19

Note: For those not into “L’s” a 16ga is 1.26mm – 1.33mm, a 17ga is 1.19mm – 1.25mm and an 18ga is 1.08mm – 1.18mm.

USRSA DEFINITIONS (We believe these are simply too broad with too much overlap and need to be refined and brought up to date. There should not be overlap.)