There’s a tennis myth that refuses to die:
Higher string tension gives you more control.
I still hear this constantly at club level. A player is struggling to keep the ball inside the lines, so the fix is to string tighter. Then tighter again next time. With modern polyester strings, that’s often exactly the wrong direction, and I want to explain why.
Polyester Behaves Differently
Polyester works differently from natural gut and softer synthetic strings. Part of what makes poly so good is snapback: the strings move sideways on impact, then snap back into place. That movement is a big part of why polyester generates so much spin.
Crank the tension way up, though, and you kill that movement. The string bed goes firm and lifeless. You might think you’re gaining control because the ball doesn’t fly off the strings as much, but you’re also stripping away most of what makes polyester worth playing with in the first place.
String it at a more sensible tension and you tend to get:
- Better pocketing
- More free depth
- More spin potential
- A softer response
- Better feel
- Less shock into the arm
That’s a pretty good list of things to give up for the sake of a number on a stringing machine.
Polyester Is Already Stiff, That’s the Whole Point
This is really the crux of it. Polyester is much stiffer than natural gut or most multifilaments. That stiffness is exactly what gives poly its control and durability – but it’s also why it can be so unforgiving on the arm.
So when you take an already-stiff polyester and string it at 25 or 26 kg, you’re building a genuinely hard string bed. A few advanced players with specific needs might want that. Most club players don’t need anywhere near it.
Unless you swing hard enough to need taming, there’s rarely a good reason to chase very high tensions with poly.
So What Tension Should You Actually Use?
A good starting point for a full bed of polyester is around:
22 kg / 49 lbs
From there, experiment. Still feels too firm? Drop to 21. Then maybe 20.
Some pros play below 20 kg, so don’t be scared of low numbers, low tension with poly is not some fringe experiment. For most players who understand how the string behaves, I’d say 20–23 kg is the sensible range. Anything north of that (24, 25, 26 kg) should be reserved for advanced players who have a specific reason to be there.
What Actually Happens When You String Too Tight
When tension is too high, the strings lose freedom to move. You lose the trampoline effect and the pocketing. Instead of feeling the ball sink slightly into the bed, you get a very direct, very flat impact – hit, gone, no in-between.
You also lose free power, so you end up swinging harder just to get the same depth. And because the bed is firmer, more of that shock transfers straight into your arm.
That doesn’t mean everyone stringing tight is heading for an injury. But if you’re already playing a stiff frame with a stiff polyester, it’s worth thinking about.
Don’t Wait for Polyester to Snap
Here’s another mistake I see constantly.
Polyester can look completely fine while it’s basically dead. It doesn’t need to break to be finished, it just needs to lose elasticity, and once that’s gone, so is the snapback that makes the string work at all.
The string starts feeling dead. You lose control, you lose spin, the response turns unpleasant. That’s your cue to cut it out and restring, don’t wait for it to physically snap.
Unless you’re a high-level player breaking strings weekly, your polyester will go dead long before it ever breaks.
The Simple Snapback Test
You don’t need a machine to check this. Push one of the main strings sideways with your finger and let go.
Snaps straight back? Good, you’re still fine.
Stays displaced, or creeps back slowly? That’s a decent sign the bed has lost its elasticity and it’s time for a restring. Not exactly lab-grade science, but it costs nothing and it works.
Measuring Dynamic Tension, If You Want to Get Nerdy
If you want to go deeper, you can measure the dynamic tension of your string bed with something like the ERT 300.
This is genuinely useful, you start to learn the dynamic tension you actually play your best at, rather than obsessing over the number you originally asked the stringer to hit. You get a much better feel for when the string is at its best, when it starts to drop off, and when it’s time to cut it out.
Do you need one? No. But this is Tennisnerd, so of course I’m going to mention the measuring device.
What About Multifilament and Natural Gut?
The whole conversation changes once you’re off polyester.
Multifilament and natural gut are softer, more elastic strings, and you can string them tighter without the same harsh response. Something like 25–26 kg can make plenty of sense there, depending on racquet and player.
Which is exactly why a tension number means nothing without knowing the string. Twenty-five kilos of natural gut and 25 kilos of stiff polyester are not remotely the same string bed.
String Type Matters Just as Much as Tension
Even within polyester, there’s a huge range. Some polys are genuinely soft. Others are brutally stiff. So 22 kg with one poly might feel comfortable, while 22 kg with another still feels demanding.
That’s why tension should always be matched to:
- The string
- The racquet
- Your level
- Your swing speed
- Your comfort needs
- Your personal taste
There’s no magic number, just sensible starting points.
Fresh Strings Usually Beat a New Racquet
Players will happily drop money on a new racquet while trying to squeeze another three months out of a dead polyester job. I’d flip those priorities.
A fresh string job changes how a racquet feels more than people expect: better response, more predictable control, better spin, better feel, and just a more enjoyable time on court.
So if your racquet suddenly feels off, don’t blame the frame first. Ask yourself when you last restrung it. The fix is usually a lot cheaper than a new racquet.
Lower Tension Doesn’t Mean Losing Control
Control was never just about cranking the string bed as tight as it’ll go. Drop the tension a little and you often get more pocketing and spin — which can genuinely help your control, not hurt it. Easier depth without swinging harder. Better shape on the ball. And because the string bed isn’t fighting you as much, you tend to play more relaxed tennis.
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A Good Starting Point
If you’re currently on a full bed of poly at 25–26 kg and you’re not an elite player, I’d experiment.
Don’t jump straight to 16. Start at 22. See how it feels. If you like the extra pocketing and comfort but want more, try 21 next time out.
Same rule I’d give for most gear changes: change one thing at a time. Otherwise you’ll never know what actually made the difference.
Restring More, String Lower
If there are two things to take from this:
Don’t string polyester unnecessarily tight.
Don’t leave dead polyester sitting in your racquet.
For most recreational players, 22 kg / 49 lbs is a sensible place to start. Then adjust from there based on racquet, string and how you play. You might find lower tension gives you more comfort, more spin, better feel and easier depth, without costing you the control you were afraid of losing.
And honestly, tennis just feels nicer that way. That alone is worth trying it.
Here’s a video for you if you want to dig deeper into strings, tension and what you need for your game:
