Tennis Racket Strings: Types, Gauges and Patterns

By Tennis Rackets UK Editorial Team · Updated 17 September 2026 · Sources checked

Close view of a strung tennis racket held over a clay court

Contents

Strings are the only part of the racket that touches the ball. Changing string type or tension can alter how a racket plays more than switching frames.

String types compared

Type	Construction	Power	Control	Spin	Comfort	Durability	Tension holding
Natural gut	Twisted animal intestine, coated	High	Medium	Medium	Highest	Low	Best
Synthetic gut	Solid nylon core with wraps	Medium	Medium	Low–medium	Medium	Medium	Medium
Multifilament	Hundreds of nylon/PU fibres bundled	Medium–high	Medium	Medium	High	Low–medium	Good
Polyester (mono)	Single extruded polyester strand	Low	High	High	Low	High	Poor (goes “dead”)
Co-poly	Polyester with additives for softness	Low–medium	High	High	Medium	High	Fair
Aramid (Kevlar)	Aramid fibres	Low	High	Medium	Lowest	Highest	Good

Ratings are relative, for comparison between string types.

String specialists such as Tecnifibre, which started with strings in 1983, also make multifilament and polyester ranges.

Hybrids

A hybrid puts one string in the mains and another in the crosses. The most common setup is polyester mains with natural gut or multifilament crosses, which keeps most of poly’s spin and control while softening the feel. A “reverse hybrid” (gut mains, poly crosses) gives more comfort and power.

Gauge

Gauge is string thickness. Thinner strings give more feel, spin and power but break sooner.

Gauge	Approx. diameter
15L	1.34–1.40 mm
16	1.26–1.33 mm
16L	1.22–1.25 mm
17	1.16–1.20 mm
18	1.10–1.16 mm

Manufacturers don’t apply gauge labels identically, so check the millimetre figure on the packet.

String patterns

Pattern	Type	Effect
16×18, 16×19	Open	More spin, more power, strings wear faster
18×20	Dense	More control, flatter trajectory, longer string life
Others (e.g. 14×18, 18×19)	Specialist	Extreme spin or niche control frames

Tension

Lower tension gives more power and comfort. Higher tension gives more control. Every frame has a recommended range printed on it. Convert between kg and lb, and adjust for string type, with our string tension calculator.

When to restring

Rule of thumb: restring as many times per year as you play per week.
Polyester: loses tension and liveliness well before it breaks. If the ball starts flying or your arm aches, it’s time.
After a break: always restring both mains and crosses, not just the broken string.

A brief string timeline

For frames as well as strings, see the history of tennis rackets.

1875: Babolat makes the first natural gut tennis strings in Lyon.
1955: Babolat’s first synthetic string.
1991: Luxilon’s Big Banger polyester string is introduced.
1997: Gustavo Kuerten wins the French Open using Luxilon ALU Power, and polyester becomes the pro standard.

Frequently asked questions

Which tennis string is best for tennis elbow?

Natural gut or a soft multifilament, strung at a lower tension, is generally the most arm-friendly. Stiff polyester and aramid strings transmit more shock.

What is a hybrid string setup?

Two different strings in one racket, typically polyester in the mains for spin and control, and natural gut or multifilament in the crosses for comfort.

How often should I restring my tennis racket?

A common rule of thumb is to restring as many times a year as you play per week. Polyester loses tension faster than it breaks, so regular poly users often restring sooner.

What does 16x19 mean?

16 main (vertical) strings and 19 cross (horizontal) strings. Open patterns like 16x19 give more spin and power; dense patterns like 18x20 give more control and durability.

Sources

Babolat — 150 years of history (official) — natural gut origins, VS gut (1925), first synthetic string (1955)
Tennis technology — Wikipedia — Luxilon Big Banger (1991), Kuerten and ALU Power (1997)
ITF Rules of Tennis, Appendix II