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Tennis String Gauge Explanation: Guide with Video & Chart

Tennis String Gauge Explained

Guide with Video & Chart

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By Jon Crim

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.

Article Contents

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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.

Tennis String Gauge: Sizes & Measurements

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.

Tennis String Gauge: Variation in Millimeter Measurements

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.

Tennis String Gauge: Sizes in Millimeters - Luxilon Alu Power

That translation might seem obvious, but I’ve seen it trip up players in the past, so it’s worth noting.

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.

String Gauges
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.

Tennis String Gauge Performance: Notches

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.

Spin Potential

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.

Tennis String Gauge Performance: Spin Potential

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

If you’re learning how to play tennis, then I’d recommend you start with a thicker inexpensive string like synthetic gut.

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.

Hybrid Stringing

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.

Tennis String Gauge: Recommendation for Beginners - Prince Synthetic Gut

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.

Player Mains Crosses
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.

Wrapping up

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.

Home > GearStrings > Tennis String Gauge

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The last comment and 2 other comment(s) need to be approved.
22 replies
    • TennisCompanion
      TennisCompanion says:

      Hey Rob,

      Thank you for your question. Generally, natural gut tennis strings will stay “freshest” the longest. However, due to their price and lack of durability, they’re not always the greatest option for players. You might find it helpful to check out the following two articles that cover natural gut tennis strings:

      As far as tension goes, natural gut strings will stay fresh or lively for most any racquet when strung roughly within the tension recommended by the racquet manufacturer. You can find this recommended tension within the throat of most tennis racquets.

      If you’re looking for a new set of strings you might want to check out our article on the different types of tennis string.

      Hopefully, this helps!

      All the best,

    • TennisCompanion
      TennisCompanion says:


      Thanks for taking the time to share the positive feedback!

      It’s much appreciated.

      All the best,

    • TennisCompanion
      TennisCompanion says:

      Hi Bill,

      Great question. Yes, to a certain degree, tension does impact spin potential for polyester tennis strings. Polys have a unique attribute where they quickly snap back into place as you strike the ball. This snapback effect provides a small incremental improvement to your topspin, which is believed to increase slightly at lower tensions.

      You can read all about tension and spin potential here.

      All the best,

  1. Mike
    Mike says:

    I just demo raquet, liked it and purchased. Unfortunately strings on the demo were not available and a close substitute was provided. However , they are a 18 gauge. i do notice the diff from demo. I like the spin but after 4 separate 1 hour hits, my arm is killing me. Is it the strings?????
    thanks for all

    • TennisCompanion
      TennisCompanion says:

      Hi Mike,

      It’s more likely that the type of string would be the culprit than the thinner 18 gauge you’re using Can you share the name of the substitute string? Beyond the string, your racquet would have a substantial impact on shock and vibration and, therefore, comfort. Perhaps you can share the racquet you purchases too, and I can give you a full run-down on my thoughts.

      All the best,

    ARJAV SHARMA says:


    If you could kindly help me over this.

    I am hard hitter with heavy topspin. I am currently using a pair of Wilson Prostaff 100LS raqcuets with a 16×15 pattern. I play 6 days a week. With two hours every day.

    I have used Head Competetion2, Wilson Power strings but I end up breaking them every third day. I use a tension of 62-64 LBS which is 30-31Kgs.

    I wonder which strings should I use to avoid spending in heaps. Please recommend 5-6 Grades and their brands which I can find in India.

    On the contrary, at times I also use my older pair of Wilson Prostaff 5.0 Midplus, which has dense string pattern and I end up hitting with these two strings for more than 20 days on one racquet. With fabulous punch and topspin. Unfortunately due to heavier frame i cant use it now for a timely backhand.

    I am 33, kindly recommend me the best. I am also suffering from an elbow.

    Thanks a lot for your presence for us.


    • TennisCompanion
      TennisCompanion says:

      Hi Arjav,

      Thanks for sharing. From what I can gather, it sounds like you have two issues you’re experiencing.

      • Breaking strings too frequently (I’m sure the cost is adding up)
      • Suffering from some discomfort in your arm

      There are a few things I’d recommend you’d consider. First, between the two tennis racquets, I’d stick with your Wilson ProStaff 100LS, which features a lower stiffness rating of 63 (compared to 74 for the 5.0), and it’s lighter. It should help prevent a bit of discomfort you’re experiencing.

      I’d also consider alternative tennis strings. For now, I’m going to assume you want to stick with a hybrid string setup, so I’ll provide more durable options while keeping comfort in mind.

      As far as durability goes:

      • One option is to bump up the gauge of your multifilament NXT power. If you’re using 17 gauge, you can move up to 16, or you can even go up to 15 with NXT DuraMax.
      • Another option would be to consider a more durable multifilament – here are a few options: Tecnifibre X-One Biphase, Tecnifibre NRG2, or Babolat Addiction. You should find all of these last longer than NXT power at 16 gauge.
      • You can also string your polyester as the mains, which should help with the durability. However, the mains will primarily dictate the overall feel, which you may find results in a bit less comfort.

      With regards to comfort, you might consider switching up your polyester string too. Polyesters aren’t known for their comfort, but some deliver more than others. A few to check out include Head Sonic Pro Edge, Tourna Big Hitter Black 7, and Dunlop Black Widow.

      I made some assumptions in those recommendations based on what you shared. If there’s anything you want to clear up so I can provide a bit more info, please let me know.

      Lastly, I hope these strings are available in your area :) Unfortunately, I’m not as familiar with what you’re going to be able to find in India. Good luck in your search!

      All the best,

  3. William
    William says:

    Question: if I use a multifilament string (Tecnifibre MultiFeel) and I string 16g at 52lbs. At what tension would I string 17g string… to have the same sort of feel as the 16g… tighter or looser… and how many lbs difference…? Thanks.

    • TennisCompanion
      TennisCompanion says:

      Hi William,

      Unfortunately, what you’d be trying to mimic (stiffness of the stringbed) differs from string to string. That is, some strings are stiffer at thinner gauges, while others at lower gauges.

      Because of this, combined with the fact that a thinner gauge will inherently feel different makes this question tricky to answer without taking measurements for this string at varying tensions.

      With that said, you’ll need to test it out. My recommendation would be to start by stringing the 17 gauge 2-3 pounds tighter. If that works, you’re golden. If not, you’ll have to try 2-3 pounds looser and see how it feels. Ultimately, you won’t end up with the same feel, perhaps just similar.

      I wish I could give a more direct answer, but hopefully, this helps point you in the right direction.

      All the best,

  4. Robert
    Robert says:

    I just started playing with 17 gauge after many years of automatically using 16. My first time playing with the 17 gauge immediately I noticed better touch and feel on the ball, especially with drop shots. This said, I also noticed that ground strokes tended to go a little long, like an inch or so. I know my technique has something to do with this, but… I know there is a rule / guideline about stringing poly 10% lower than say multifilament. Is there also a rule / guideline when changing gauges. At 16 gauge I was stringing at 50lbs. At 17 gauge, I wish I had strung it at 52 or maybe more. Is there a rule / guideline when changing gauge by one level?

    • TennisCompanion
      TennisCompanion says:

      Hi Robert,

      Your question falls into a similar category as William’s above – it’s tricky to answer :)

      Ultimately, what you’d’ be trying to mimic is the stiffness of the stringed. However, some strings will string up stiffer at higher tensions while others will string up stiffer at lower tensions, which makes it difficult to put hard and fast rules in place for players when switching the gauge of their string.

      However, instead of focusing on tension as it relates to gauge, my recommendation would be to consider the effect of changing tension independent of gauge. In your case, you’re finding your shots are sailing slightly long.

      Based on what we know about tension, you’d want to bump it up 2-3 pounds to prevent hitting long. Higher tensions result in a stiffer stringbed, which decreases the launch angle of the ball resulting in less perceived power and more control.

      Good luck – would love to hear how things work out.

      All the best,

    • TennisCompanion
      TennisCompanion says:

      Hi Al,

      I wouldn’t worry too much about gauge when it comes to comfort and your tennis elbow. However, I would recommend a slightly lower tension, and more importantly, a softer multifilament tennis string if you’re not already using one.

      A few, I’d recommend:

      • Wilson NXT
      • Babolat Xcel
      • Tecnifibre NRG2
      • Tecnifibre X-One Biphase

      Good luck and I hope your tennis elbow gets better.

      All the best,

    • TennisCompanion
      TennisCompanion says:

      Hi Stef,

      Great question. There’s absolutely nothing wrong with stringing RPM Blast in a junior tennis racquet. However, I typically find that most children or early teens using a 26-inch tennis racquet aren’t at a level to benefit from a polyester string like RPM Blast or to recognize the difference from an inexpensive synthetic gut alternative.

      Another factor to keep in mind is that strings like RPM Blast can be hard on a player’s arm, especially as they lose their tension and go dead, so if they’re not replaced frequently, that can become a concern for younger kids.

      Usually, I’d encourage parents to wait until their child has been hitting with a full-size 27-inch racquet for a while before introducing a string like RPM Blast, but there certainly are unique cases out there.

      Hopefully, that helps!

      All the best,


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