Tennis String Gauge Explained
Guide with Video & Chart
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When it comes to tennis string, one of the key attributes to understand is gauge or the string’s thickness and how it impacts performance.
While it’s a simple concept, many players overlook string gauge and don’t fully reap the benefits of stringing their racquet with the best size for their individual needs and preferences.
In this guide, I’ll explain what string gauge means and how it’s measured, review the variety of sizes available, and help you identify what string gauge to use along with a handful of our favorite picks.
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String Gauge Video
To help explain tennis string gauge, I’ve put together the following video, which pairs nicely with what I’ve shared in this article.
Here are timestamps for the different sections and topics covered:
0:27 – Definition & Sizes
1:06 – String Gauge Chart (mm included)
2:13 – Gauge & Performance
3:38 – Finding the Right Gauge
5:17 – String Gauge & Tension
Here’s a link to my guide on string tension, which I reference in the video.
For a deeper dive and explanation, check out the remainder of this guide and the sections that follow.
What is Tennis String Gauge?
Gauge is a measure of a string’s thickness or diameter, which according to industry standards, falls between 0.60 and 1.80 millimeters.
String gauge is a personal preference with various advantages and disadvantages on both ends of the spectrum, which I’ll dive into as part of the sections that follow in this guide.
String Gauge Sizes and Measurements
Since tennis string gauge is the thickness of a string, we can measure its diameter to come up with its size.
You’ll typically find the gauge for a string printed prominently on the package, as shown in the image below.
The following chart outlines the types of string gauge or measurements currently available.
|US Gauges||Int. Gauges||Measurements|
|13||12||1.65 – 1.80 mm|
|14||11||1.50 – 1.65 mm|
|15||9.5||1.41 – 1.49 mm|
|15L||9||1.33 – 1.41 mm|
|16||8.5||1.26 – 1.34 mm|
|16L||8||1.22 – 1.30 mm|
|17||7.5||1.16 – 1.24 mm|
|18||7||1.06 – 1.16 mm|
|19||4||0.90 – 1.06 mm|
|20||3.5||0.80 – 0.90 mm|
|21||3||0.70 – 0.80 mm|
|22||2.5||0.60 – 0.70 mm|
As you review the chart, there are a few observations worth noting.
- For US measurements, you may find string gauge measurements to be counterintuitive. As you can see, the higher the gauge, the thinner the string, and the lower the gauge, the thicker the string. International gauges are the opposite.
- 15 and 16 gauge strings come in “light” or slightly thinner versions as denoted by 15L and 16L.
- There’s some overlap between gauge measurements, so there are cases where manufacturers can pick the gauge for marketing their strings.
- Each gauge represents a range of measurements in millimeters. For example, a 16 gauge string refers to any string that falls between 1.26 and 1.34 mm thick.
Luckily, string gauges have become more standardized, so although ranges exist for each gauge, some measurements are more common, e.g., a 16 gauge string is often 1.30 mm thick.
However, there still is some variation that exists. In the following visual, you can see how three different strings from various brands all have the same gauge, but the thickness in millimeters is different.
For that reason, along with the overlap that can exist between measurements, I prefer to reference the thickness of a string in millimeters, which you’ll find printed on the package as well.
In fact, in some cases, that’s all you’ll find, as is the case with Luxion ALU Power, but notice how they simply print 125 to represent 1.25 mm.
That translation might seem obvious, but I’ve seen it trip up players in the past, so it’s worth noting.
Popular Gauges and Examples
The most common measurements, and therefore the widest selection of strings that you’ll find available, are 17, 16L, and 16. While there are strings for sale outside this range, most players fall within this range when stringing their racquets across many different string types.
For context, here’s a selection of five popular strings and available gauges that you can purchase.
|Wilson NXT||16, 17|
|Luxilon ALU Power||15, 16L|
|Prince Synthetic Gut||15L, 16, 17|
|Babolat VS Touch||15L, 16, 17|
|Tecnifibre X-One Biphase||15L, 16, 17, 18|
If you’re looking for a few of our other favorite picks, check our guide to the best tennis strings in 2020.
Helpful tip: It’s important to note that the above measurements are guidelines, which most manufacturers follow. However, from time to time, you may come across string sets that fall outside of these recommendations, so check the package to know what you’re using.
String Gauge and Performance
Of course, knowing string gauge isn’t all that helpful if you’re not clear on how the thickness of a string impacts performance.
There are three main factors players usually consider when selecting a string gauge: durability, spin potential, and feel.
When comparing different gauges for the same string, the heavier the gauge or thicker the string will be more durable and long-lasting.
When you play tennis, your strings produce friction at the cross-sections where they overlap each other. Over time you’ll notice that your strings cut into each other and begin to notch, so naturally, the thicker they are, the longer they’ll last. Thicker strings can also withstand greater impact, which helps extend the life, too.
However, when it comes to durability, keep in mind that a wide variety of factors can influence the longevity of a string, including material, construction, tension, and a string pattern’s density.
All else equal, thicker strings are more durable, and it’s a great rule of thumb to use when evaluating strings.
Beyond durability, players also rely on their string gauge to influence their potential for generating spin. The thinner the string, the more potential for spin, while the thicker the string, the less spin potential.
Thinner strings bury themselves deeper into the ball, and as a result, “grab” the ball, which results in more spin. A thicker string has less bite, resulting in a lower potential for spin.
However, just because you have thin strings doesn’t mean you’re automatically going to generate massive spin. It’s one of many factors that can influence spin. However, your grip, technique, and racquet head speed will have the most significant influence over spin.
Another area where you’ll notice changes with different gauge is the feel of the strings as many players report enhanced feel with thinner strings.
I happen to love the sensation of a 17 gauge string, but even in a more durable option like polyester, I tend to break them fairly easily, so 16 is the lowest gauge I typically string. It’s a tradeoff, and in this case, I err on the side of durability.
Which String Gauge Should You Use?
Every player’s needs and preferences are different. With this in mind, you can keep in mind a variety of factors when evaluating strings and determining which is best for you.
Types of String
The type of string your using frequently has an impact on the gauge that you choose. Here’s a brief look at the different types of strings:
- Natural Gut: high power, comfort, tension maintenance, exceptional feel, prone to breakage, and susceptible to moisture
- Synthetic Gut: mid-range tennis strings offering well-rounded performance across the board, typically lack durability
- Multifilament: the synthetic alternative to natural gut, these strings offer power, comfort, and hold their tension well
- Polyester: low powered spin-friendly strings that are stiff and durable, but tend to lose their tension quicker than other strings
- Kevlar: the most durable strings that maintain their tension well
As you read the descriptions, it might begin to click why you might consider a higher or lower gauge for each.
For example, you might string with a lower gauge (thicker) tennis string if you’re using synthetic or natural gut to help increase the durability or life of your strings. Whereas, if you’re using polyester strings, you may opt for a higher gauge (thinner) option to help maximize spin.
If you can’t afford to string your racquet frequently, I’d recommend you string with a thicker or low gauge string to help avoid breakage and increase your strings’ longevity.
Racquet stringing can be expensive, especially when you take into consideration the labor to string your racquet. You can go thicker, but 16 will usually do the trick while helping maintain solid playability and spin potential.
If you want to play with a thinner gauge, but budget is a concern, you may want to consider using string savers to get the benefit of a higher gauge without breaking the bank.
Frequency of Play
Another factor to consider is your frequency of play. If you’re playing only twice a month, you might not be as concerned with longevity, so you may be comfortable stringing with a higher gauge.
After all, you’ll still want to replace your strings on a semi-regular basis since strings naturally lose their tension and liveliness over time.
On the other hand, if you’re playing five days a week and you can’t afford to restring every week, then you might want to use a lower gauge to increase the life of your strings.
Level of Play
When you’re just getting started, you’ll unlikely be able to notice the subtle differences between a higher or lower gauge string. However, you will be more likely to appreciate the extra durability of a lower gauge string that doesn’t break easily and limits your restringing frequency.
As a result, for beginners, I’d recommend 16 gauge (1.26 to1.34 mm) to start. Over time as your skills develop, you’ll find your appreciation for strings do too.
If you’re intermediate to advanced, then I’d recommend you experiment with different gauges to get a feel for the change in performance. There’s no right or wrong answer – instead, keep the pros and cons in mind, and let your preferences drive your decision making.
Style of Play
Once you cross over to an intermediate level of play, you’ll begin to develop a style. Examples of different styles include Rafael Nadal’s aggressive baseline play or Roger Federer’s all-court fineness play.
In the case of Nadal, he hits with an incredible amount of topspin and uses a 15 gauge polyester tennis string from Babolat called RPM Blast.
On the other hand, Federer doesn’t hit with as much topspin, but has an impressive arsenal of shots and regularly plays from all areas of the court. He strings a hybrid setup with 16 gauge natural gut in the mains and 17 gauge polyester in the crosses, which brings us to our next point.
There aren’t rules for hybrid stringing, where a player uses one type of string for the mains and another for the crosses.
However, it’s common for players to use a different gauge for each based on the characteristics the strings offer, as Federer does.
When it comes to gauge and stringbed stiffness, which impacts comfort, studies have been inconclusive. In other words, different strings will offer more comfort at higher or lower gauges.
With that said, you’ll have to be the judge when you find a string you like and experiment with different gauges. However, if you’re after comfort, the type of string you’re using, and the tension you’re stringing have a material impact that is worthy of consideration.
Gauge Recommendation for Beginners
If you’re new to tennis and looking for a recommendation on a string gauge, I’d encourage you to start with 16.
You’ll find a wide selection of strings at this thickness. Plus, it happens to be roughly a midway point between other more commonly available gauges, so you’ll have room to move up or down in thickness based on your experience.
For example, Prince Synthetic Gut is a popular and inexpensive string that you can easily find in 17, 16, and 15L.
What the Pros Use
The gauge the pros use can be a useful point of reference, but don’t let it ultimately drive your decision making.
For example, budget is not a concern when it comes to the top players, so what works for them might not make sense for you.
With that said, here’s a handful of pros and the gauge they use.
|R. Federer||Babolat VS 16||Luxilon ALU Rough 16L|
|R. Nadal||Babolat RPM Blast 15L||Same as mains|
|N. Djokovic||Babolat VS 16||Luxilon ALU Power 16L|
|S. Willaims||Wilson Natural Gut 16||Luxilon 4G 16L|
|N. Osaka||Yonez Poly Tour Strike 16L||Same as mains|
|K. Plíšková||Babolat VS 16||Babolat Pro Hurricane Tour 17|
String Gauge and Tension
A common question that comes up when talking about string gauge is what tension works best for a specific gauge string or how tension should be modified when moving up or down a gauge for the same string.
Unfortunately, there’s no clear-cut answer to this question based on how different strings respond to tension at higher and lower gauges.
As a result, my recommendation is to think about tensions effect independent of gauge when they make a change.
For example, if you’ve switched gauges and you find your clipping the net often, you might want to decrease your tension a few pounds. The result would be a less stiff stringbed, which produced a higher launch trajectory, i.e., more power, and should help.
If you’re stringing a racquet for the first time, I encourage you to consider the recommended tension ranges for the racquet and strings you are using to help dictate a starting point for tension. I cover all these points in our resource on string tension, so be sure to check that out.
Hopefully, this guide helps point you in the right direction, but don’t get too bogged down in the details. Starings aren’t permanent, so you’ll have plenty of opportunities to try something new.
As you progress, it can be helpful to experiment with different gauge tennis strings, especially within the same type of string, as performance will vary.
What gauge tennis strings are you using, and why? We’d love to hear in the comments below. Of course, if you have questions, drop us a note.
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