String Tension Explained: What Actually Changes When You Drop Two Kilos

Changing string tension costs nothing beyond the restring you were going to pay for anyway, and it changes the feel of a racquet more than most equipment upgrades.

It is also surrounded by confident nonsense.

The basic trade-off

• Lower tension: more power, more comfort, more dwell time, less control, slightly more spin potential in many setups.
• Higher tension: more control, crisper feel, less power, harsher on the arm.

The mechanism is straightforward. A looser bed deforms more on impact and returns more energy to the ball, like a trampoline. A tighter bed deforms less, returns less energy, and gives more predictable direction.

What tension does not do

• It does not fix technique. A player spraying balls long because they are swinging flat with an open face will still spray at higher tension.
• It does not stay put. Polyester loses tension fast, dropping meaningfully within the first hour of play and continuing to fall. Your 24kg string bed is not 24kg by week three.
• It does not transfer between string types. 24kg in polyester plays substantially tighter than 24kg in multifilament. Changing string type requires rethinking the number, usually downward by two to three kilos when moving to poly.

String type matters more than tension

Most players fiddling with tension should be looking at string material instead.

• Natural gut: best comfort and tension maintenance, high power, expensive, poor durability in wet conditions.
• Multifilament: most of gut's comfort at a fraction of the price. The right default for most club players and anyone with elbow trouble.
• Polyester (co-poly): control and spin for players with long, fast swings. Stiff and unforgiving. It is the most over-prescribed string in tennis and a common cause of arm pain in players who do not generate enough racquet speed to need it.
• Synthetic gut: cheap, unremarkable, perfectly adequate for beginners.
• Hybrid: poly in the mains for control and durability, softer string in the crosses for comfort. A sensible compromise.

Finding your number

1. Start at the middle of the range printed on the racquet.
2. Play three sessions and note whether errors are mostly long, mostly into the net, or mostly off-centre in direction.
3. Balls flying long with normal swings suggests going up two kilos. Struggling for depth suggests coming down two.
4. Change one variable at a time and give it three sessions. Changing string and tension together tells you nothing.

Restringing frequency

The rule of thumb is to restring as many times per year as you play per week. Play three times a week, restring three times a year at a minimum.

Most club players restring only when a string breaks, which means playing for months on a dead bed that has lost its tension and its texture. A string that has not broken can still be finished.