How to choose tennis string gauge
TenisRaketi Editör Ekibi · Updated October 2026
Short answer
1.25–1.30 mm is a good balance for most players. Thin strings (1.15–1.20 mm) give more feel and a little more spin but break sooner; thick strings (1.30 mm and up) last longer. Gauge numbers vary between brands, so always go by millimetres.
In this guide
Gauge is the second biggest thing that changes how a string feels, after the type. But its effect is smaller than the type's: the difference between a 1.25 mm and a 1.30 mm polyester is small next to the difference between polyester and multifilament. So pick the type first (types of tennis strings), then fine-tune with the gauge.
Gauge numbers and millimetres
Thickness is written two ways: in millimetres and as a gauge number. The higher the gauge number, the thinner the string. "L" (light) means a slightly thinner version of the same number: 16L is thinner than 16.
Gauge | Approx. thickness |
|---|---|
15 | 1.40 mm and up |
15L | 1.34–1.40 mm |
16 | 1.26–1.33 mm |
16L | 1.22–1.26 mm |
17 | 1.16–1.24 mm |
18 | 1.06–1.16 mm |
The ranges overlap and brands round the number differently. A string one brand calls "17" can be as thick as another brand's "16L". When comparing two strings, go by millimetres.
What a thin string does
- More feel: A thin string is more elastic, so the ball sinks into the string bed a little more.
- A little more spin: The string grips the ball better and the mains slide more easily. The effect is small; the main sources of spin are in the strings and spin guide.
- A little more power and comfort: In the same material, a thinner string feels softer.
- Shorter life: Less material means faster wear and breakage.
What a thick string does
- Longer life: If you break strings often, going one gauge thicker is the easiest fix.
- A firmer feel: The ball comes off with a little less give.
- Slightly less spin and power.
Which gauge should you choose?
Your situation | Suggested gauge |
|---|---|
My first strings, not sure | 1.25–1.30 mm |
I break strings before they go dead | One gauge thicker: 1.30–1.35 mm |
My strings last for months, I want more feel | One gauge thinner: 1.20–1.25 mm |
I play with lots of spin on an open-pattern racket | 1.25–1.30 mm; the strings wear each other quickly |
My arm hurts | A thin gauge of a soft type, e.g. 1.25 mm multifilament |
String pattern and gauge
On open-pattern rackets (16×19, 16×18) the strings are further apart and move more at impact. That helps spin but the strings wear each other faster, so a spin player breaks strings more often on these rackets. On a dense pattern (18×20) the strings move less and last longer. You can look up string pattern in the glossary.
Different gauges in a hybrid
The two strings of a hybrid can have different gauges. The mains usually break first, because they are the ones that move and wear. So some players use a slightly thicker string in the mains and a slightly thinner one in the crosses.
Frequently asked questions
Is 1.25 mm or 1.30 mm better?
Both are fine; it depends on what you need. 1.25 mm gives a little more feel and spin, 1.30 mm lasts longer. If you break strings often choose 1.30 mm; if they last and you want more feel, 1.25 mm.
How many mm is 16 gauge?
About 1.26–1.33 mm. 16L is a little thinner, about 1.22–1.26 mm. Brands round the number differently, so check the millimetre value on the packet.
Do thinner strings give more spin?
A little. A thin string grips the ball better and moves more easily. But its effect on spin is small next to the string type, the racket's pattern and your swing speed.
I break strings all the time. What should I do?
First go one gauge thicker, for example from 1.25 mm to 1.30 mm. If that is not enough, try polyester or a hybrid with polyester mains. If you break strings every week, aramid mains are an option.
More guides on this topic
- How to choose tennis stringsFor most players multifilament or synthetic gut is a safe starting point. Hard hitters who break strings often go for polyester, and players who put arm health first choose multifilament or natural gut. A gauge of about 1.25 mm is a good balance.
- Tennis string tension: what should it be?Start in the middle of the range printed on your racket: the exact middle for multifilament, synthetic and natural gut, and about 1 kg (2 lb) lower for polyester. Lower tension gives more power and comfort, higher tension gives more control. Change it by no more than 1 kg at a time.
- Types of tennis stringsThere are four main types: natural gut (softest, most expensive), multifilament (soft and powerful), synthetic gut (cheap, all-round) and polyester (stiff, controlled, durable). Aramid is only used in hybrids. How fast you break strings and how sensitive your arm is decide the type.
- How strings affect spinMost spin comes from your swing; strings make it easier or harder. On the string side the biggest effect is the mains sliding and snapping back: a slick polyester and an open string pattern increase it. A shaped cross-section has a smaller effect, and it fades as the string wears.
- How to choose arm-friendly stringsNatural gut and multifilament are the easiest strings on the arm. If you want to use polyester, choose a soft model, a thin gauge and a tension at the low end of the range, and restring before it goes dead. A vibration dampener does not protect your arm.
- When to restring a tennis racketThe practical rule: restring as many times a year as the days you play per week. If you play three days a week, three times a year. With polyester, restring more often; it goes dead within weeks even if it does not break. If the racket feels harsh, balls fly long or the strings stay out of place, it is time.