When choosing your tennis racquet of choice, much of it boils down to personal preference and feel.
One area where that's certainly the case is string tension, as there are so many permutations for both the type of tennis string you are using and the tension you string it at.
The pro tour further reinforces this as if you've ever seen behind the scenes in the stringing room at a major tournament; you'll see string tension requests from players are wide-ranging.
Some ATP players string in the 30-lbs range, while others are as high as 70 lbs. The others find themselves somewhere in the middle.
But how do you go about finding the right tension? What impact does string tension have on the racquet and your game? Let's take a look.
A Quick Primer on String Tension
Whenever a tennis racquet is strung, be it at the factory to be sold as a pre-strung frame or by your local stringer, a specific tension is applied to both the cross and main strings.
This tension measures weight being applied to the string as it’s pulled through the racket by the stringing machine and expressed in either kilograms or pounds.
Before stringing commences, a racquet technician will set the stringing machine at the required tension. Usually specific to what the player has requested or in the middle of the range recommended for the racquet if unsure.
Then as the stringer begins pulling strings through the frame, the machine will pull every string to the appropriate tension.
While I won't go into detail about the different types of stringing machine and their efficacy, it's worth noting that although a calibrated machine will pull a string to the pre-determined tension, the real tension of the finished racquet will typically be slightly lower due to slight tension loss in the installation process.
Tension loss can occur through friction when pulling cross strings, slippage in the clamps and when tying off the knots when the job is complete.
What Are Some Typical Tension Ranges?
All tennis racquets come with a recommended tension range from the manufacturer. This is both for optimal performance and to ensure you don't string at too high a tension, which will severely deform the frame or even crack it.
You can see the tension ranges for five racquets that feature in my best tennis racquets guide, and they all fall in a very similar ballpark:
|Yonex Ezone 98 (305g)||45-60 lbs.|
|Babolat Pure Strike||52-62 lbs.|
|Wilson Clash 100 Tour||48-58 lbs.|
|Yonex VCore Pro 100||45-60 lbs.|
|Wilson Blade 98 16×19 v7||50-60 lbs.|
What Effect Does String Tension Have on the Racquet?
From a physics perspective, string tension impacts two variables:
- Dwell Time
- Coefficient of Restitution
Dwell time is the length of time the ball stays on the strings. The coefficient of restitution measures the elasticity of the collision between the ball and the racquet (a higher COR means more elasticity (liveliness).
In turn, these affect the feelings a player has in terms of power, control and stress on the body. But this is where there is no real exact science of what is best as it boils down to personal preference.
For one, the relationship between string tension and coefficient of restitution is not linear, especially on differing head sizes of racquets which is why you see some string players string at 70lbs and others at 40lbs.
Lower String Tensions
The lower the string tension, the longer the dwell time. This results in an increase in power due to the so-called trampoline effect and more energy being returned to the ball. While negligible in raw miles per hour terms, it will result in the ball landing deeper in the court compared to an identical shot played with a higher tension.
It will also increase comfort due to a reduction in stringbed stiffness, which affects the torque and vibrations felt by the wrist, elbow, and shoulder.
Lower tensions give you:
- More Power (or depth)
- More Comfort
- More Durability (although not always the case)
- More Feel
But on the flip side:
- Less Control
Higher String Tensions
While the general principle that low tension gives more power is quite easy to prove, the claim that higher string tensions give more control is harder to explain. Is it because higher strings make spin easier? Or simply the fact players must swing harder (in turn producing more spin) to hit with sufficient depth when their racquets are strung tighter?
As is always the case, there is certainly plenty of anecdotal evidence that players feel more control when using a high string tension, and there's likely enough of it to say, yes, higher string tensions do produce more control.
This study from Dr Simon Goodwill has some interesting takeaways, but from the other bits we can piece together, the ball is flattened more with a tight racquet, so topspin is easier to produce.
This is particularly true on smaller head sizes because an off-centre hit will deform the string bed less than it would a larger head size racquet. Pete Sampras is a good exponent of this; he could generate amazing topspin on his second serve using his heavy, 85 square inch racquet, tightly strung (75 lbs 😲) racquet.
Ultimately, spin gives greater control, and greater spin is possible with tight strings.
Higher tensions give you:
- More Control
- More Spin
But on the flip side:
- Less Durability
- Less Power
- Less Comfort
Side note: Polyester strings like Babolat RPM Blast strung at lower tensions produce a snapback that also impacts topspin.
String Tension and Durability
Another area where string tension and its relationship to the racquet isn't clear cut is how it impacts durability. Does high tension increase durability? Or does low tension prevent the string from being stretched beyond its limits and therefore last longer?
The general line of thinking is that lower tensions allow the strings to move more freely and notch each other faster. This is true for certain strings, but from my experience, it's not a golden rule.
Much of it depends on the type of the string and whether it's in a hybrid setup. Polyester strings, for example, tend to last far longer at lower tensions.
From my own experience, strings at higher tensions still move freely, which, combined with the increased friction, can lead to earlier breakage than lower tensions.
My advice is not to let durability play much of a role in the string tension you choose. If durability is a concern, think more about the type of string you use rather than focusing on tension.
Which String Tension Should You Choose?
Before deciding on string tension, ideally, you want to know what you are looking for in your game and how you want your racket to perform accordingly.
For example, if you're physically strong and wielding a sledgehammer type racquet like Stan Wawrinka, then you'd most likely choose to string at a high-ish tension rather than a low tension. Chances are you don't need an additional boost in power by lowering the tension only to see the trampoline effect send the ball into the fence.
On the other hand, a player who isn’t as powerful or an older player that would like some free power from the racquet might benefit enormously from a power orientated string at a low string tension.
The best way is to experiment and a good starting point in the middle of the recommended range from the manufacturer.
So if you have a Pure Strike that recommends between 52 and 62 lbs, string it at 57 lbs. However, there a couple of further recommendations below depending on what type of string you are using,
- Synthetic gut, natural gut or multifilament string: Start at the middle (or 2lbs above) of the recommended tension range that's printed on your racquet.
- Polyester or kevlar: String 2 lbs below the middle of the recommended tension range that is printed on your racquet.
Once you have a baseline, you can experiment more if you feel that something wasn't quite right.
Try not to make drastic changes, such as stringing at the loosest tension possible or going super high if the middle of the range didn't feel right.
Subtle tweaks are more likely to help you find the right tension, whereas drastic changes can often leave you feeling even more confused about what works and what doesn't.
If you have two matching racquets, you could even experiment from the word go with slightly differing tensions. But do make sure you have the same string in both racquets, and you strung them at the same time.
String Tension and Arm Problems
As mentioned above, lowering the string tension means a racquet will be more comfortable to play with due to reduced stringbed stiffness.
So if you are suffering from wrist, elbow or shoulder problems, dropping the tension can be a quick fix to help preserve your arm.
If you have just developed a twinge in the arm, tweaking the tension would be my recommended first port of call.
Over the years, I've heard of players seeing instant results without needing to make wholesale changes to their equipment. All from a slight drop in tension and re-stringing more frequently as strings lose their properties over time.
If your problems persist, then the type of string and the racquet itself (stiffness, balance, weight and grip size can all be factors) play a part in comfort, so you may need to make more significant changes.
Should I String My Racquets at Different Tensions?
Suppose you're a player who is playing in league tennis or competitively. Chances are you are taking multiple racquets to court. Many players carry at least two, but it's not uncommon to see four, five or six racquets in someone's bag.
The main reason for this is that a player breaks a string; it's not just game over. However, many players choose to string some of their racquets a few kilograms or pounds tighter for added control or lower if they feel like they need more power.
This can be due to the opponent, how they are feeling on the day, or the conditions.
The video below from Tennis Spin is a good explanation of why a player might carry four racquets with differing tensions:
How Climate Effects String Tension Choice
Outdoor or indoor, arid or humid climate all impact how the ball reacts through the air and off the string. Depending on the climate, this can either slow down or accelerate the ball, so it can be worth tinkering with your tension to match the conditions.
For most players, this will be when they head indoors for winter tennis, where the elements are not at play, and you generally get a faster-paced game. Many players choose to string a few lbs higher indoors to establish more control.
Also, remember that the types of string you use can react differently to changes in weather and temperature. Natural Gut, for example, suffers from moisture in the air and the weather, as does multifilament.
Polyesters suffer more from colder temperatures. A rigid string plus cold ball makes it difficult to accelerate the ball. If you have ever played outside on a winters day, you'll notice the balls feel completely lifeless.
String Tension and the Court Surface
The court surface you play on should also play a part in the tension you choose. For example, on the pro tour, the change to the clay season sees most professional players mostly adjust the tension of their string by decreasing it by 2 to 4 lbs.
On clay, the ball will absorb the dust and is heavier, while on indoor hard court, for example, the felt wears quickly, and the ball becomes smoother over time and is lighter and faster.
In general, on the slower surfaces, it is advisable to reduce the tension by a couple of pounds to compensate for the heaviness of the ball, the slowdown of the game and the fact it takes more effort to hit winners. During the transition to a faster surface or indoors, you should re-add the pounds you removed on clay to regain control.
As soon as a racquet is strung, it will lose tension before it goes anywhere near a tennis ball. It's said that strings can lose up to 10% within 24 hours.
So if you string at 55 lbs but don't plan to use your racquet for a week, then it will have lost quite a bit of tension by the time you finally play.
If you were to play amazingly, you might think that 55lbs is the sweet spot. So you restring again at 55lbs, only this time play the same day, but you feel underpowered as the tension loss is not as significant.
This is why some players ask their racquet stringers to string their racquets at set times before matches on the pro tour. For example, Ron Yu of Priority 1 will try to keep the timing consistent throughout the tournament.
So if Federer played the night session starting at 8 pm, Yu might string 5 hours before play. If he wins and the next day Federer had a 12 pm start, Yu would be up at 5 am stringing to keep that consistency.
One other way to avoid some tension loss is to pre-stretch strings before stringing. Federer has his string pre-stretched, and this is done by looping the string around something like a door handle and then pulling it tight with your body weight.
Finally, each type of string loses tension at different rates, with some like natural gut and multifilament strings tending to do a better job at maintaining their tension. In contrast, polyester strings typically don’t perform as well with tension maintenance.
Personally, if I know I'm not going to use the racquet for a couple of days and don't really feel like re-stringing it again for a couple of weeks, I push the tension up a few kilos so that by the time I hit with it, it's not dropped way below the tensions I like.
What String Tension Do the Pros Use?
Interested in what tensions some of the pros string at? I've compiled a selection below to show how some of them differ.
- Most pros will vary their tension slightly based on the conditions, as we discussed above.
- Pros are often using pro stock racquets that aren't matching the specs of the retail frame they endorse, so you can't just copy their tension. Even Roger Federer's racquet, which is virtually identical to the retail RF97, has a few tweaks, such as power pads which slightly elongate the main strings.
|Racquet||Wilson Pro Staff RF97|
|Mains||Wilson Natural Gut 16|
|Crosses||Luxilon ALU Power Rough 17|
|Tension||M: 27 kg / 59.5 lbs C: 25.5 kg / 56.2 lbs|
I've also covered Roger Federer's string tension in-depth for those interested in some of his other stringing quirks.
|Racquet||Babolat Pure Aero 2019|
|Mains||Babolat RPM Blast 15|
|Crosses||Babolat RPM Blast 15|
|Tension||M: 25 kg / 55 lbs C: 25 kg / 55 lbs|
|Racquet||Head Graphene 360 Radical Pro|
|Mains||Luxilon ALU Power 17|
|Crosses||Babolat VS Touch 17|
|Tension||M: 29 kg / 63.9 lbs C: 28 kg / 61.7 lbs|
|Racquet||Wilson Ultra 95 Countervail|
|Mains||Wilson Natural Gut 16|
|Crosses||Luxilon Element 16|
|Tension||M: 17.7 kg / 39 lbs C: 16.8 kg / 37 lbs|
|Racquet||Babolat Pure Aero VS|
|Mains||Luxilon ALU Power Rough 17|
|Crosses||Luxilon ALU Power Rough 15|
|Tension||M: 15.9 kg / 35 lbs C: 15.9 kg / 35 lbs|
Please note: I've used the racquet names the players endorse, not the moulds they use. Djokovic is not using a 100 sq” frame when he plays; his tension would not be the number I have provided if he were.
How To Check String Tension
For checking the tension of your racquet, there are a couple of tools on the market that can help you. The first is a tool used before you actually string and relies on you having a stringing machine.
This calibration tool fits onto your stringing machine and uses a spring to check you are pulling the tension you've set the machine to.
This is usually less of a concern on a constant pull electric machine, but it can be worth checking on crank machines as the springs weaken over time.
The second tool is a tension testing tool; these help technicians and players measure string tension after a racquet is restrung.
You can get analogue type devices, electric ones and even apps that work via acoustics. Some tools to check out include:
Changing the string tension in your racquet can be a powerful tool for your game when done correctly, and that little bit of fine-tuning can help you find a winner just when you need it or that bit more control to stay in a rally.
Just remember changing tension is no magic bullet and won't clear up deficiencies in technique, fitness or poor equipment choice in general.
Finally, there is no right or wrong answer when it comes to what tension you should use. I wouldn’t recommend blindly copying the professional players unless you have flawless stroke mechanics and have matched all their specs based on the pro stock frame.
I'd suggest starting in the low to mid-50s and seeing how that feels for the average club player. Just remember that the tension loss will occur pretty quickly and that 55lbs will soon turn in 50lbs, so your preferred tension will depend on how often you are prepared to restring your racket.
Have questions about string tension or feel like there's something I've missed or got wrong? Let me know in the comments below.