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Different Types of Tennis Strings – What do they do? What are they made of?

Once you’ve chosen a tennis racket, there are two factors that affect its performance more than any others – the type of string you choose and the tension you string it at.

The reasons are obvious. The string bed is the only part of the racket that connects with the ball. The strings you select will affect the amount of power, control, spin, feel and comfort you get from your racket. 

We’ve covered the question of string tension elsewhere so in this article we’re going to help you to understand the different types of string available, what they’re made from and the effects each can have on your game.

What are tennis strings made of?

There are two main types of tennis strings available. Natural gut strings and synthetic strings.

As the name suggests, natural gut strings are made from animal guts, specifically serous membranes, usually from cow intestines. 

Synthetic strings meanwhile can be made from a variety of man-made materials including polyester, nylon and polyurethane. 

Natural Gut Strings 

When tennis was first invented back in 1875, there was only one type of string available – Natural Gut.  

Pierre Babolat – yes, that one – had a successful business manufacturing strings for musical instruments. But when tennis became popular he decided to broaden his focus. 

His strings were originally made from sheep’s intestines although in the 1960s they switched to cow. And surprisingly to some that’s a method still used today.

For that reason natural gut strings are some of the most expensive on the market. But they’re also the first choice of many professionals due to their exceptional performance. 

Natural gut has uniquely elastic properties that provide high levels of power, feel and comfort. They’re also much better at retaining tension than most synthetic strings. 

There are drawbacks though. Other than their high cost, natural gut strings break easily and have a tendency to absorb a lot of moisture, affecting their playability. They’re also not as good as some of the more modern synthetic strings at generating spin.

If you’re new to the game or have a tight budget we’d advise looking at a cheaper option but if you’re a more advanced player and you’ve never tried natural gut it’s worth finding out why the likes of Roger Federer swear by it.

Natural Gut Benefits:

  • Control
  • Comfort
  • Power
  • Feel
  • Retaining Tension

Natural Gut Drawbacks:

  • Expensive!
  • Breaks easily

Synthetic Strings

While natural gut were the original strings on the block, in the 1950s companies started to experiment with man-made fibres. Nowadays there are three main categories of synthetic string – 

  • Synthetic Gut
  • Multifilament
  • Polyester (sometimes called monofilament or co-poly)

Let’s take a look at each in turn.

Synthetic Gut Strings

Intended to ape the performance of natural gut, synthetic gut strings are usually made from nylon. They’re constructed using a solid inner core wrapped in additional fibres to improve performance.

They’re the cheapest type of string available but are a solid all-rounder, providing decent power, control and feel.

That makes them a good choice for beginners and some intermediates although as your game improves you may look for a more specialist string type. 

Synthetic Gut Benefits:

  • Decent all-rounder
  • Great price
  • More durable than natural gut

Synthetic Gut Drawbacks:

  • No outstanding attributes

Multifilament Strings

If you’re looking for the power and playability of natural gut but without the price tag, multifilaments are a good option.

Multifilaments are constructed using a variety of pliable synthetic fibres interwoven to mimic the elasticity and feel of natural gut – but with additional durability.

That means you can expect a really comfortable swing and lots of power without breaking too many strings. 

SEM micrograph of a sectioned multifilament string. Courtesy of Prof Claire Davis and Elizabeth Chandler, School of Metallurgy and Materials, University of Birmingham.

Multifilaments are a great choice for intermediates looking to make a step up from synthetic gut.

It’s worth noting that the multifilament tag incorporates a wide variety of construction types meaning there’s a broad range of prices and quality available. 

Multifilament Benefits:

  • Very good control, feel and power
  • Arm friendly
  • Cheaper than natural gut
  • Retains tension

Multifilament Drawbacks:

  • Not great for spin

Polyester Strings

Polyester strings (sometimes known as co-polys or monofilaments) are constructed using just a single solid core. 

Only introduced in the late 90s, the strings have become increasingly popular as they allow for huge amounts of topspin. 

As tennis has moved towards a more spin-based game with big hitters like Rafael Nadal ruling the roost, polyester has gained in popularity. 

Compared to natural gut and multifilament strings they don’t give you a ton of power which means players can put on plenty of whip without risking overhitting. 

That makes them unsuitable for beginners who generally lack power of their own.

But advanced players with a good spin game will take advantage of the strings’ ability to grip the ball and they can help contribute to a more aggressive game. 

Polyester Benefits:

  • Great Spin
  • Great Control
  • Great Durability

Polyester Drawbacks:

  • Low Power
  • Not arm-friendly

Other Types of String

The strings listed above are the most common around but there are a couple of others you may encounter.


Kevlar or Aramid fibre strings are the strongest and most durable strings on the market.

As a result they can be extremely tough on the joints and don’t offer much in terms of feel or control. 

Although they may still be popular with players who hate breaking strings, in general Kevlar has been phased out in favour of more modern materials and construction.


The newest development in string construction is textured strings. 

Textured strings are a type of monofilament where the shape is altered giving a rough exterior. Generally these are thought to grip the ball better providing extra spin.

Hybrid Strings

Hybrids are not a type of string in themselves but a method of stringing rackets to combine two different styles. 

For example, a player who values the power and feel of natural gut but requires greater durability might use natural gut in the main strings combined with a polyester cross string. 

That way they get the best of both worlds. 

In general though it’s the main string that dominates the racket’s performance. 

Gauge or Thickness

When selecting the right type of string for you, the other consideration is the gauge or thickness of the string. 

The gauge you select will have an impact on how the string performs. 

Generally speaking thinner strings (or higher gauge) will offer greater spin and more power. That’s because they’re more elastic.

Thicker strings (or lower gauge) offer more control and durability. 

If you tend to hit big, flat shots you should probably go with a thicker string to reduce the chances of breakage. But if you rely heavily on spin you may appreciate a thinner set up. 

To complicate matters, the thickness of each gauge varies between different manufacturers but we’ve provided a table below to give you a rough idea of the ranges you’ll find.


Once you’ve selected your string type and gauge, you need to decide how tightly you want them strung. In other words – what’s your preferred string tension?

You can get an idea of the recommended string tension by looking on the throat of your racket. But within that range you can feel free to experiment.

Look on your racket for the recommended string tension

Generally speaking the lower the tension, the greater the power and spin you’ll get. 

Conversely, the higher the tension the less power.

If you’d like to learn more you should check out our in-depth guide to string tension.

Another String to Your Bow

Hopefully this guide has given you a clearer idea of the kinds of strings you can buy and what effect each will have on your game. As with most things it pays to experiment. 

So next time you’re due a restring, why not try something new?


Are tennis strings made from cat gut?

Natural Gut strings are sometimes referred to as ‘cat gut strings’ but they DO NOT contain cat gut. As mentioned above cow intestines are usually used for natural gut strings. It’s thought that the phrase ‘cat gut’ originated as an abbreviation of ‘cattle gut’.

What strings does Stan Wawrinka use?

Stan Wawrinka uses a Yonex VCore 95 D strung with 16 gauge Babolat RPM Blast. The mains are strung at 61 pounds while the crosses are 57 pounds.

What strings did Roger Federer use?

Roger Federer used a Wilson 97RF Pro Staff strung with a hybrid string set up.

He used Wilson’s own 16 gauge natural gut string in the mains with Luxilon Alu Power Rough 17 in the crosses. He used a tension of around 59.5 pounds in the mains and 56.2 pounds in the crosses.

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