String Specifications for Pro Tennis Players

String specifications differ by player
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Professional tennis players usually carry an arsenal of rackets. Each racket can differ greatly, such as being strung based on the type of string or tension. There is no one string tension or string type that is right for everyone. Finding the right combination comes from years of practice and feeling what works in each playing situation, according to the United States Tennis Association (USTA). You won't be able to find the pros' rackets at a local shop, but you may be able to imitate their string specifications.

String Materials

    The first choice that pro players make is what type of material to use for their strings. According to, there are four main materials: natural gut (made from cow intestines), polyester, nylon and kevlar. There is also a hybrid option, introduced by Andre Agassi, which uses two different types of string on the same racket, per "The Racket and String Specs of Top Male Tennis Pros" by Glenn Sheiner M.D. For example, Federer uses gut on his main (or vertical) strings and polyester on his cross (or horizontal) strings. Natural gut used to be the only material employed by top players, but hybrid rackets are now common, used by players like World No. 1 Novak Djokovic.

Pounds of Tension

    Tension on your racket strings is measured in pounds. Most rackets are packaged with a recommended tension that comes from hours of testing, but professional players will deviate based on their needs. While it isn't an exact science, less tension provides more power, and more tension provides more control, according to the USTA. Tensions are different for main versus cross strings. Pete Sampras and Bjorn Borg were both known for tight rackets tensions measuring usually above 70 pounds. Federer's tension is often in the mid 40s and Nadal in the mid 50s, according to Glenn Sheiner, M.D. Depending on weather conditions, a player might switch to a different tension racket mid-match to improve performance.

String Gauge

    String gauge is measured by the numbers 15 through 19, which correspond to millimeters. As a general rule, thicker string offers more durability, while thinner string allows for more spin on the ball, according to The thickest gauge is a 15 down to the thinnest at 19. The letter "L" means light. These range from the thickest at 15 (1.41 to 1.49) to 19 (1 to 1.1 mm). The top players often use a thicker gauge; Federer usually uses 16, while Nadal stings with 15L.

String Pattern

    In addition to customizing material, tension and gauge, pro players also select string patterns. This refers to how closely the main strings are strung with the cross strings. A more open string pattern (18-by-20, meaning 18 main, 20 cross) is used by Djokovic, according to professional stringer Roman Prokes, because it allows for more controlled power and more spin. The denser 16-by-19 string pattern is used by Nadal and Federer and offers more durability, but with less rebound for real hard hitters.

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