Most players put serious thought into which tennis string to buy — but almost nobody thinks about gauge. That’s a missed opportunity. Gauge refers to the thickness of the string, and it has a direct impact on how your racket feels, how much spin you generate, and how long your strings last before they snap.

Whether you’re choosing between different string types or fine-tuning a setup you already like, gauge is one of the simplest ways to change the way your racket plays — without changing the string itself.

Here’s everything you need to know, from a stringer’s perspective.

What Do Tennis String Gauges Mean?

Tennis string gauge is measured using a numbering system that runs opposite to what you’d expect: a lower number means a thicker string. The most common gauges range from 15 (thickest) to 18 (thinnest), with half-sizes denoted by an “L” (for “light”).

Here’s the full scale:

Most strings are sold in 16 or 17 gauge. If a string doesn’t specify a gauge clearly on the packet, it’s almost always 16 (1.30mm).

How Gauge Affects Performance

String gauge creates a set of trade-offs. There’s no “best” gauge — only the right one for your game and how you play.

Thinner Strings (17g, 18g)

• More spin: Thinner strings embed into the ball more and have greater snapback — the lateral movement of mains strings that creates topspin. If you’re chasing more spin, check our guide to the best tennis strings for spin.
• More feel and touch: A thinner string deforms slightly more on contact, giving you a more connected, responsive sensation — particularly useful at the net and on drop shots.
• Less durability: Less material means less to wear through. Heavy topspin hitters using a thin polyester can break strings in just a few hours of play.

Thicker Strings (15g, 16g)

• More durable: If you break strings regularly, moving up one gauge can significantly extend string life — sometimes doubling it.
• More stable: Thicker strings resist movement in the string bed, producing a more consistent, predictable response shot to shot.
• Less spin potential: With less string movement, you get less snapback. The trade-off for durability is a slightly flatter ball flight.
• Slightly stiffer feel: Thicker gauges can feel a touch boardier — a factor to consider if you’re concerned about comfort.

What Gauge Are Our Strings?

Every string we stock at Restring London is available in specific gauges. Here’s what we carry and how each is gauged:

You’ll notice that most of our polyester strings sit at 16L (1.25mm) or 17 gauge. That’s not a coincidence — it’s the sweet spot where spin, feel and durability are best balanced. See our full stringing prices for more details. You can also bring your own string and we’ll install it for £20.

How to Choose the Right Gauge

Choosing a gauge is simpler than most guides make it sound. Ask yourself what matters most, and work from there.

If You Break Strings Often

Go for 16 gauge (1.30mm) or thicker. A thicker string gives you more material to wear through before it snaps. Moving from 17g to 16g can easily double the lifespan of a polyester string. If you’re still breaking strings quickly, consider a textured or shaped poly like Solinco Hyper-G, which tends to last longer than smooth round strings at the same gauge.

If You Want Maximum Spin

Choose 17 gauge (1.20–1.25mm) or thinner. Thinner strings dig into the ball more and snap back harder, generating more topspin without changing your technique. Pair a thin gauge with a shaped or textured polyester for maximum effect — our guide to the best strings for spin covers specific options.

If Comfort Is Your Priority

Consider a 16 gauge multifilament like Wilson Sensation Plus (£25 installed). Multifilaments are softer than polyesters, and the 16g thickness provides a forgiving, cushioned response without sacrificing too much durability. If you’re deciding between string types, our polyester vs multifilament guide breaks down the differences.

If You’re Not Sure

Start with 16L (1.25mm). It’s the most popular gauge on tour and among club players for good reason — it sits right in the middle of the spin-durability trade-off. Most of our Tier 1 and Tier 2 polyesters come in this gauge. If you’re newer to the game, our beginner string guide is also worth a read.

Can You Mix Gauges? Hybrid Setups

Yes — and it’s more common than you might think. A hybrid setup uses one string in the mains (vertical) and a different string in the crosses (horizontal). Many players use a thicker polyester in the mains for durability and spin, paired with a thinner multifilament in the crosses for comfort and feel.

For example, you might run Solinco Hyper-G 16L in the mains and Wilson Sensation Plus 16g in the crosses. This gives you the spin and control of a poly with the arm-friendliness of a multi.

You can also vary gauge within the same string type — for instance, 16g poly mains and 17g poly crosses — though the performance difference is subtle. If you’re curious about hybrids, this guide covers how to choose the right combination.

Does Gauge Affect Tension?

Slightly. A thinner string at the same tension will feel a little softer and more powerful than a thicker one, because there’s less material resisting the ball. If you switch from 16g to 17g and keep the same tension, expect the stringbed to feel marginally livelier. Some players compensate by adding a pound or two of tension when going thinner.

That said, the difference is small — typically a couple of pounds at most. Don’t overthink it on your first gauge change.

Book a Restring

Not sure which gauge is right for you? That’s exactly the kind of thing we help with. When you drop off your racket at our Victoria Park studio, we’ll talk through your game, your string history and what you’re looking for — then recommend a gauge, string and tension to match.

Book your restring online or message us on WhatsApp to get started. Same-day turnaround, seven days a week.