Quick answer: The string gauge is the thickness of your tennis string. Thinner strings give more spin, feel and power but break sooner. Thicker strings are more durable and offer a firmer, more controlled feel but with slightly less spin and touch. Frequent string-breakers should go thicker; players chasing spin and feel should go thinner.
Gauge is the string spec players understand least, yet it quietly shapes spin, feel and how often you're back at the stringing bench. Once you get it, you can fine-tune your setup with real precision. Here's the specialist's guide to string thickness.
What is string gauge?
Gauge simply means how thick the string is, measured in millimetres and often given a gauge number too. The confusing part: the higher the gauge number, the thinner the string. So a 17-gauge string is thinner than a 16-gauge string.
To keep it simple, we'll talk in terms of thin versus thick.
| Common gauge | Approx thickness | Character |
|---|---|---|
| 15 / 15L | Thickest | Maximum durability |
| 16 / 16L | Medium | All-round balance |
| 17 / 17L | Thinner | Spin and feel |
| 18 | Thinnest | Maximum spin and touch |
The "L" (light) sits between full gauges, so 16L is slightly thinner than 16.
What the numbers mean in millimetres
If you prefer real measurements to gauge numbers, here is roughly where the common gauges sit:
- 16 gauge (approx. 1.30–1.34mm): the thickest common string diameter — durable and long-lasting.
- 16L / 16.5 gauge (approx. 1.25–1.28mm): a popular middle ground between 16 and 17.
- 17 gauge (approx. 1.20–1.25mm): noticeably thinner, more feel and spin than 16, shorter lifespan.
- 18 gauge (approx. 1.10–1.16mm): the thinnest widely available gauge — maximum feel and spin, but wears through fastest.
Thin strings: spin, feel and power
Thinner strings have real advantages for players chasing a lively, responsive setup:
- More spin: thinner strings bite into the ball and snap back more, helping generate topspin.
- More feel: a softer, more connected sense of the ball on the strings.
- More power: thinner strings flex a touch more for extra pop.
A thinner string also embeds into the ball slightly more on contact and moves more freely against its neighbours, which is where the extra spin potential comes from.
The catch: thinner strings break sooner. There's simply less material to resist the abrasion and stress of hitting, so durability drops.
Thick strings: durability and control
Thicker strings trade some liveliness for toughness:
- More durability: more material means they survive far longer before snapping.
- A firmer, more controlled feel: less flex for a solid, predictable response.
- Better tension stability: thicker strings tend to hold their tension slightly longer, so play stays consistent for longer between restrings.
- The trade-off: slightly less spin, feel and power than a thinner string.
If you're a habitual string-breaker, a thicker gauge can save you a fortune in restrings without changing your whole setup.
Which gauge should you choose?
Match the gauge to your priorities and your string-breaking habits.
- You break strings often: go thicker (e.g. 15 or 16) for durability.
- You want maximum spin and feel: go thinner (e.g. 17 or 18), accepting more frequent restrings.
- You want a sensible all-rounder: 16 gauge is the classic balanced choice.
- You use polyester and hit big: many players use a thinner poly for spin, but expect to restring more often.
There is no free lunch here: any gain in feel, spin or comfort from going thinner comes directly at the cost of durability, and vice versa. If you genuinely are not sure, start at 16L or 17 — that is the gauge most club players settle on long-term. Go thinner only if you specifically want more spin and touch and are prepared to restring more often to get it.
Mixing gauges in a hybrid setup
You do not have to pick one gauge for the whole racket. Many players get the best of both by hybrid stringing: a thicker, more durable gauge in the mains, which take most of the wear, paired with a thinner gauge in the crosses, where feel matters most. It is a common way to stretch the lifespan of a spin-friendly setup without losing all of its feel. Read our guide to hybrid tennis strings for the full picture.
Gauge works with type and tension
Gauge is one of three string variables you can tune, alongside type and tension. They all interact:
- A thinner polyester maximises spin but breaks quickest.
- A thicker multifilament lasts longer while keeping comfort.
- Pair your gauge choice with the right tension: lower for power and comfort, higher for control.
Read our companion guides on tennis string types and tennis string tension to tune all three together.
A note on string longevity
Whatever gauge you choose, remember that strings lose tension and playability over time, not just when they break. A thicker string may survive longer physically, but its feel still fades. Regular players benefit from restringing on a schedule rather than waiting for a snap. Our in-store team can advise on the right gauge and restringing rhythm for your game.
FAQs
Does a thinner string give more spin?
Yes. Thinner strings bite into the ball and snap back more readily, helping you generate topspin, along with more feel and a little more power. The trade-off is reduced durability.
What string gauge is most durable?
Thicker gauges, such as 15 or 16, are the most durable because there's more material to resist wear and stress. They're a smart choice for frequent string-breakers.
Why is a higher gauge number thinner?
It's just the convention of the numbering system: as the gauge number goes up, the string gets thinner. So 18-gauge is thinner than 16-gauge. It catches everyone out at first.
What gauge should a beginner use?
A 16-gauge is a sensible all-round choice, balancing durability and feel. Beginners rarely break strings from spin, so there's no need to chase the thinnest gauges early on.
Can I use different gauges in the mains and crosses?
Yes. A hybrid setup with a thicker main and a thinner cross is a well-established way to balance durability against feel. Just tell your stringer what you want when you book.
Want the right gauge for your game? Browse our tennis range or book a restring through Central Tennis in-store services, and our specialists will dial in your perfect setup.
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