Make a list of your favorite conversation topics, and I’ll guarantee string thickness, or gauge, won’t be anywhere near the top. The most tedious of afterthoughts, it often barely enters the stringing conversation at all. Get it right, and your racquet will play as intended: get it wrong, and your hard earned cash will be conspiring against you every time you hit the ball.
String thickness is measured in two ways: millimeters and gauge. To add a much needed element of confusion, the person who invented the gauge system made the thickness go up as the gauge number goes down. Who says there’s no comedy in the world of measurements?
There are no precisely defined gauges in the world of stringing, but there are ranges that vary slightly by manufacturer and the type of string. The following table gives an overview of the current state of play. If in doubt, look at the actual diameter in mm. ‘L’ stands for light.
| Gauge | Diameter range in mm |
| 15 | 1.41 – 1.49 |
| 15L | 1.33 – 1.41 |
| 16 | 1.26 – 1.34 |
| 16L | 1.22 – 1.30 |
| 17 | 1.16 – 1.24 |
| 18 | 1.06 – 1.16 |
| 19 | 0.90 – 1.06 |
Why should you care about how thick your strings are? Put simply, the gauge of a string affects how the string plays and how long it will last, and you need something that compliments both your game and your racquet
Durability
Thick strings last longer than thin strings – it’s that simple. As you play a shot, strings move relative to each other, creating friction. Typically the main strings move over the cross strings, creating notches in the mains. This movement and subsequent wear is greatly increased if you hit with aggressive topspin and power. When the notch gets to a certain point, the string will fail. Racquets with more open string patterns (fewer cross strings and main strings) will wear strings faster than those with dense patterns like an 18/20. The increased stretching of thin strings can also cause a more rapid loss of tension than with thick strings.
Feel
The thinner the string, the more it will stretch for any given shot, enhancing an effect called ball pocketing. Increased ball pocketing translates to an increase in feel.
Comfort
Thinner strings will reduce the initial shock on impact by deflecting more. This is good for tennis elbow sufferers, although the string material is also very important here. A thin Kevlar string will still produce more of a shock on impact than a thick poly.
Spin Potential
Thinner strings will produce more spin than their thick counterparts – as they stretch and deform more on impact, they are able to grab onto the ball and impart rotation. There is also an increase in a phenomenon known as snap back, where the main strings move sideways on impact and store energy. This is then released as the strings return to their original position, imparting spin on the ball as it leaves the string bed. The actual spin you’ll develop is obviously heavily dependent on your stroke, and the importance of spin potential is dependent on your game style.
Control
Thick strings deform less on impact, giving a slight increase in control. A similar effect can be gained by increasing tension. If you’re a big hitter, control will be high on your agenda.
Power
Thin strings deform more on impact, allowing them to store more impact energy. As the ball is released, the strings return to their starting position, transferring energy back to the ball. In other words, thin strings give more power.
Thin vs Thick… a summary
| Thin String | Thick String |
| Power | Durability |
| Spin | Tension maintenance |
| Feel | Control |
| Comfort |
So what does this all mean? Probably the most obvious conclusion is that string thickness is all about compromise – there are no free lunches here. You have to balance string type, gauge, tension and style of racquet to suit your individual game. You shouldn’t try to turn an 18/20 control orientated racquet into a spin machine, any more than you should try to tame a powerful spin monster to suit a flat hitting game.
If you’re a hard hitter, start with a 16 gauge and see how long it lasts – frequent restrings suggest a date with a 15 gauge, or even a different string material. If you want control and comfort, try a 17 gauge, and perhaps even an 18 gauge if you’re getting sufficient durability. If you’re lucky enough to have two or more racquets, you try stringing them differently and see which you like the most. A little experimentation could give you years of enhanced play.