Selecting the best strings for your racket is one of the most important tasks when it comes to taking care of your racket. Not only are there quite a few different materials to choose from, they are available in different sizes. Racket strings are made in different thicknesses, called gauges. The thicker the gauge, the more durability and control, while the thinner the gauge, the more power and comfort. In the end string gauge is a personal preference with various advantages and disadvantages on both ends of the spectrum, which I’ll explain further in the rest of this article.
Basic gauge sizing for tennis rackets
To start things off, let’s take a look at all the gauge sizes out there, with their respective international indicators. As you can see, it’s not the most logical way of putting things in order, so take a moment to study the different labels and diameters.
| U.S. | International | Diameter (mm) |
| 13 | 12 | 1.65-1.80 |
| 14 | 11 | 1.50-1.65 |
| 15 | 9.5 | 1.41-1.49 |
| 15L | 9 | 1.33-1.41 |
| 16 | 8.5 | 1.26-1.34 |
| 16L | 8 | 1.22-1.30 |
| 17 | 7.5 | 1.16-1.24 |
| 18 | 7 | 1.06-.1.16 |
| 19 | 4 | 0.90-1.06 |
| 20 | 3.5 | 0.80-0.90 |
| 21 | 3 | 0.70-0.80 |
| 22 | 2.5 | 0.60-0.70 |
Because some gauge labels can overlap with respect to their diameter (mm), we tend to stick with the diameter (just as ERSA does) as the best way to describe and classify different string gauges. However, on packaging materials, you’ll normally find the U.S. labels.
Common gauges and recommendations
We’ll take a deeper dive into string gauges in the rest of the article, but I wanted to see if I could simply things a bit at the start here. Now there are no one-size-fits-all solutions when it comes to racket gear but here are the most common gauges and who I’d recommend each for.
- 15/1.40mm: Thickest gauge; best for advanced players looking for maximum durability and control. However, these strings might be considered so durable that the trade-off with ‘feel’ and spin potential might be a bit too much.
- 16/1.30mm: Medium-thick gauge; best for heavy hitting competitive players who break strings frequently.
- 16L/1.28mm: Medium gauge found in Luxilon strings; best for competitive players looking for a blend of power and control.
- 17/1.25mm: Medium thin gauge; best for beginner, intermediate and all-round players who are looking for power and comfort.
- 17L/1.20mm: Thin gauge; best for players looking for increased touch and feel and don’t mind spending a bit more on restringing.
- 18/1.15mm: Thinnest gauge; best for players wanting maximum touch and feel and will have to restring very often.
Please keep in mind though that this is a basic overview and that a lot of players tend to deviate from this, for their own specific reasons (whether that is in their benefit or not).
A bit of theory on string gauges and their “ping”
When you string two identical rackets with different gauge of the same strings and perform the palm test (meaning you use the palm of your hand to ‘clap’ your racket and hand together) with the strung rackets, the thinner gauge will have a higher “ping”. Most people would logically assume the thinner string is tighter.
Even though little difference is found when measured statistically (i.e. RA test), the racket with the thinner gauge may feel less stiff in play, due to a greater elasticity of the thinner string. Generally a 17 gauge string will be about twice as elastic (100%) as a 15 gauge string, all other factors being equal. This increased elasticity results in lower dynamic stiffness (meaning the strings will feel more elastic) during ball contact.
A player changing to a thicker string (for greater durability, for example) may complain the that the “ping” isn’t the same as with his thinner gauge string. However, increasing tension to reproduce that harmonic pitch would probably result in a stringbed stiffness too hard for his liking. So the main takeaway here is: string for feel, not for the “ping”. Don’t focus too much on sound…
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.
Durability
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.
Spin potential
Beyond durability, players also rely on their string gauge to influence their racket setups 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 a bit better, 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 racket head speed will have the most significant influence over spin. Also, keep in mind that when players step on the court with the idea of having a string optimised for “spin”, they tend to hit the ball with a lot more spin themselves, which actually generates more spin (but from stroke technique, and not from the string itself).
Feel
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. Of course, this is a personal matter per definition.
I happen to love the sensation of a 16L gauge string, even in a more durable option like polyester, I tend to break them fairly easily, so 16 is the lowest gauge I typically string.
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 make sense 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.
Budget
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 durability. Racket stringing can be expensive (though here at our platform we try to provide every customer with a fair price), 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 limiting factor, you may want to consider using string savers to get the benefit of a higher gauge without breaking the bank. However, personally I do not recommend using them as they might limit ‘snapback’ from the strings.
What about your own experiences with string gauge? What is the size you play with? Are there any combinations you’d recommend out of your own experience? Please let me know in the comment section down below.