Supplying Strings and Restringing for Racket Sports Professionals & Enthusiasts


About Strings

There are thousands of strings on the market with manufacturers producing ever more complex structures using hi-tech materials. The strings are designed to meet different requirements and playing properties. All strings exhibit power, control, comfort and durability properties, but each individual string has a different mix of these properties - our string details pages give you an indication of these relative properties. The way strings behave when hit by a tennis ball is very scientific - see the USRSA web site for more information.

There are several characteristics of all strings and a restring:

String Construction

Basic Facts
  • Longer string lengths (in larger frames) produce more power
  • More elastic strings generate more power
  • Softer strings create less vibration down the racket
  • Elastic strings have more tension loss after stringing

Monofilament strings are made of a single, solid extrusion of material. Originally this was nylon but, these days, the material used is one of the fastest developing sectors in the string industry.

Materials now consist of polyester or polyether or a mixture of different materials. The advantage of monofilaments is their enhanced durability. Originally, this came with the price of a very unforgiving string, but there are now more and more 'soft' monofilaments coming onto the market which give the strings more playability.

A further recent development is to make the extrusion non-circular to give so-called 'corners' on the string with the aim of helping with spin, such as Babolat's Pro Hurricane Tour.

Monofilaments are often part of a hybrid string set-up with the monofilament used in the main strings and a softer non-monofilament string used in the cross strings. This gives a good compromise between durability and playability. Chronic string breakers often resort to monofilaments in both mains and crosses.

If any arm problems develop, the use of monofilaments should be stopped until the problems are sorted out. Monofilaments generally transfer more shock down the racket into the handle than a softer, multifilament string.


Multifilament strings have no centre core, but are made up of hundreds or thousands of strands of material twisted together, usually with an outer coat for added protection. Typically, aging of multifilament strings exhibit a 'furry' nature to the strings as the outer coat wears and the individual fibres break.

Multifilaments are the closest to natural gut and offer the best comfort to people suffering from tennis elbow or other arm problems. They offer great playability and shock absorption and many of the premium multifilament strings are getting closer and closer to natural gut. One drawback is their tendency to lose tension faster than a string with a solid centre core. Pre-stretching the string before stringing can help reduce this tension loss.

Multifilaments often tend to be more expensive, but a cheaper alternative to natural gut.

Solid Core with Single Wrap

As its title suggests, this string construction consists of a thin monofilament core with a single layer of fibres twisted around the outside. This, in turn, is usually coated on the outside for protection. This construction is used in many of the budget nylon strings.

The centre, solid core, gives the string durability, whilst the single wrap outer gives the string more playability than a standard monofilament.

Solid Core with Double Wrap

As its title suggests, this string construction consists of a monofilament core with a two layers of fibres twisted around the outside, usually wound in different directions. This is also usually coated on the outside for protection.

The centre, solid core, gives the string durability although this is usually thinner than the single wrapped version. The two wraps give the string more playability than either a monofilament or a single wrapped string.

Multicore with Wrap

Many of the latest strings on the market are making use of complex multicores using a variety of different fibres in each core. The millions of small fibres give enhanced playability and elasticity.

Some of the fibres used in the multicore bundles are made of stronger polyester to enhance durability.


Hybrid strings consist of two different types of string - one for the main strings and one for the cross strings. Whilst any two different strings can be used, there are a growing number of string 'half sets' being sold as hybrids.

The most common set up is to use a monofilament string in the mains and a softer, often multifilament string in the crosses. This gives durability in the mains - the strings which take the greatest pounding when using top spin, whilst still giving some playability. The notable exception to this set up is Roger Federer who uses gut in the mains and a monofilament in the crosses - but that won't last long if you have heavy top spin!

Hybrid stringing is good for performance juniors as they start to break strings. The enhanced durability gives longer between string breakages, but the softer crosses reduce the amount of shock and helps protect young muscles!

If any arm problems start to develop, the use of monofilament strings should be stopped until the problem is sorted out.

Natural Gut

Before the advent of nylons and man-made fibres, natural gut was the only string available. Today, it has still not been matched for its playability and particular power and feel qualities - although many of the premium multifilament's are getting closer.

Gut strings are made from cows or sheep (and not cats as some people believe!). There are only a few factories left in the world - the only UK factory is Bow Brand in King's Lynn.

The price for natural gut is prohibitive for many and although they tend to have a weatherproof coating these days, poor weather conditions reduce the life of a gut string.


Textured strings are designed to give more bite to the ball to help develop more spin. The strings tend to have a solid core with a number of uniform wraps. On top of this is added another wrap wound around the outside to give a rough feel to the string.

Textured strings are often used in a hybrid set up to compensate for the smooth surface of the monofilament

String Gauge

Strings are measured by their diameter when under tension - usually in millimetres. Two systems of gauge labelling are used - the US system and the International system. The table below gives an indication of the relationship between these systems - however, be aware that some manufacturers will label their strings slightly outside these guidelines! All references to gauge on this site refer to manufacturer's specifications.

Basic Facts

Thin strings:

  • Generate more power
  • Generate more spin
  • Have less durability
  • Have more comfort
  • Have more tension loss

Thicker strings:

  • Generate less power
  • Generate less spin
  • Have more durability
  • Have less comfort
Thickness (mm)   American Gauge   International Gauge
1.65 - 1.80 13 12
1.50 - 1.65 14 11
1.41 - 1.49 15 9.5
1.33 - 1.41 15L 9
1.26 - 1.34 16 8.5
1.22 - 1.30 16L 8
1.16 - 1.24 17 7.5
1.06 - 1.16 18 7
0.90 - 1.06 19 4
0.80 - 0.90 20 3.5
0.70 - .080 21 3
0.60 - 0.70 22 2.5

Stringing Tension

Basic Facts
  • Lower string tensions generate more power
  • Higher string tensions generate more ball control
  • Rackets with fewer strings (or string density) generate more power
  • Rackets with few strings also generate more spin - as long as the strings don't slip
  • Rackets with tight string beds give more control (less string slippage/movement)

Whilst everyone talks about string tension, the important measure is string bed stiffness. This is a measure of how tight (or loose) the strings feel in the racket. Stringing two different rackets at the same tension with the same string will result in two different string bed stiffness measures - and will play differently. There are a number of factors which influence string bed stiffness:

  • Racket Head Size
  • Larger heads need to be strung at a higher tension than smaller heads to produce the same string bed stiffness
  • Racket String Pattern Density
  • Less strings generate a lower string bed stiffness
  • String Gauge
  • See above
  • String Construction
  • See above
  • Stringing machine type
  • Different types of machine will produce a different string bed stiffness - continuous pull machines will produce a firmer string bed than a lock out machine
  • Tension
  • The tension you set on your stringing machine. Is it accurately calibrated and pulling at the tension it says?
  • The stringer - YOU!
  • Different methods and skill levels will dramatically affect the string bed stiffness