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String gauge: which number to pick
What 16, 17 and 1.25 mm actually mean, and how thickness changes spin, feel and how long it lasts.
Gauge is the thickness of the string. It is written two ways: in millimeters (1.20, 1.25, 1.30) or on the American number scale (18, 17, 16). They run backwards from each other: the higher the American number, the thinner the string.
The conversion table
| Gauge | Millimeters | Profile |
|---|---|---|
| 15 | 1.41 - 1.49 | Very thick, maximum durability |
| 16 | 1.26 - 1.34 | The most common, balanced |
| 17 | 1.20 - 1.24 | Thin, more feel and spin |
| 18 | 1.10 - 1.16 | Very thin, breaks fast |
Thin or thick: what changes
- Thinner: bites the ball more, more spin, better feel, cuts through the air. Breaks sooner.
- Thicker: lasts far longer, forgives bad contact, feels muted and gives less spin.
The difference between a 16 and a 17 is real but not dramatic. If you have never thought about gauge, it is not the first thing to change: tension and string type matter far more.
Which to pick
- If you break strings often: 16, or even 15.
- If you rarely break and want more spin: 17.
- If you do not know: 16. It is the standard for a reason.
Read next: how to choose your string.