All About Strings & Stringing
“Strings are the Soul of a Racquet”
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Strings may be the soul of racquet, but to many players they are just an afterthought. Players will spend 6 months demoing racquets and 6 minutes choosing a string. Fortunately, synthetic string technology has improved dramatically over the last 20 years and there are very few “bad” strings. However, not all strings (and string tensions) are right for all players. Every player has different needs and preferences. Here are a few guidelines to make your string and tension selection easier.

It’s very difficult to obtain consensus on what makes a string playable. Some players like a crisp, firm playing string while others equate playability with softness and comfort. Generally, a playable string is resilient, which means it snaps back quickly upon ball impact. The material, construction, and thickness of a string will all affect the playability of a string. The most resilient (playable) string at this time is still natural gut. This is the only string made from a natural product – beef intestines. It is the oldest tennis string made and remains the benchmark for playability. Some of the most popular playability strings at Tennis Warehouse include: Babolat X-Cel, Prince Premier w/SoftFlex, Tecnifibre NRG2, Tecnifibre X-One BiPhase and Wilson Sensation NXT. Strings that offer good playability at a lower price (below $7.00) include: Alpha Gut 2000, Ektelon PowerPlay (AKA Prince Synthetic Gut Soft) and Tecnifibre E-Matrix.

As with our beer, most of us want a string that offers everything. Unfortunately, increased durability in tennis strings is usually at the expense of playability. Thicker gauges and abrasion resistant materials will be more durable, but they are less elastic and resilient than their thinner, nylon-based counterparts. (See gauge table below.) If a player is breaking a 16 gauge nylon string (synthetic gut), we might suggest they switch to a 15L version of that same string, if available, for more durability. Otherwise, the next step would be a nylon durability string, such as Gamma Marathon DPC or Wilson Stamina. After that, we recommend trying a polyester string, such as Babolat Ballistic or one of the popular Luxilon strings. Finally, for players who blow through all of the strings listed above, Kevlar hybrids are the final alternative. The superior abrasion resistance of Kevlar makes it the most durable string available.
String Gauge

Generally speaking, thinner strings offer improved playability while thicker strings offer enhanced durability. Tennis string gauges range from 15 (thickest) to 19 (thinnest), with half-gauges identified with an L (15L, 16L, etc), which is short for “light”. A 15L string is thinner than a 15 gauge but thicker than a 16 gauge string. Thinner strings also provide more spin potential by allowing the strings to embed into the ball more.

String Gauges and Diameters in millimeters15 = 1.41-1.49 mm 17 = 1.20-1.24 mm
15L = 1.34-1.40 mm 17L = 1.16-1.20 mm
16 = 1.26-1.33 mm 18 = 1.10-1.16 mm
16L = 1.22-1.26 mm 19 = 1.00-1.10 mm


Nylon – synthetic gut or nylon? Truth be told, synthetic gut is nylon. In fact, most of today’s “performance synthetics” are constructed of nylon, albeit a higher grade than basic nylon string. Today’s manufacturing processes produce nylon strings (or synthetic gut, if you insist) that provide a good combination of playability and durability. In the old days (wood racquet era), any self-respecting player used natural gut. Nylon was so bad that only beginners used the stuff. Today, 98% of non-professional players use nylon strings. It’s that much better. Other string materials include:

Natural Gut – the ultimate in playability and feel. Often overlooked due to it’s cost, natural gut is the best choice for players with arm problems or those who simply want the best. Formerly, the number one choice of ATP and WTA tour players. Now used more in hybrids, combining polyester mains with natural gut crosses. Natural gut gut offers maximum feel and control due to it’s low dynamic stiffness, which provides better ball “pocketing”, and a slight texture that provides more ball grab for enhanced spin.

Polyester – a very durable string designed for string breakers-not much power or feel. Polyester strings became very popular with ATP players, because it provides added durability, doesn’t move and “deadens” the stringbed. While this isn’t a desireable feature for most recreational players, it is for many of todays ATP and (some) WTA players. They’re bigger, stronger, swing faster and use more powerful racquets than players from the past. Often used in hybrids, combining polyester mains with softer synthetic or natural gut mains. This offers the durability benefits of polyester, while reducing the stiff, dead feel. Also easier to string than 100% polyester. Not recommended for beginning players or players with arm injuries.

Kevlar – The most durable string available. Kevlar is very stiff and strings up very tight. Therefore, it is usually combined with nylon to reduce the string bed stiffness (Kevlar main strings, nylon cross strings). Still, Kevlar hybrids are the least powerful and least comfortable strings currently available. Players trying kevlar hybrids for the first time (from nylon strings) are recommended to reduce tension by 10% to compensate for the added stiffness. Not recommended for beginners or players with arm injuries.
String Construction

Here’s a list of string constructions, general descriptions of their associated performance benefits and examples of each:
Solid Core with One Outer Wrap

Most popular nylon string construction – majority of “synthetic gut” strings are solid core/single wrap. Main benefits are tension maintenance and crisp feel. Quality of nylon center core, as well as size and orientation of outer wraps can influence feel and comfort.

Babolat Conquest
Gosen OG Sheep Micro
Gosen OG Jim Courier
KLIP Scorcher
Prince Synthetic Gut Original
Wilson Stamina Synthetic Gut

Solid Core with Multi Wraps

Provides additional durability and cushioning.

Gamma Gut 2,
Gamma TNT Pro Plus
KLIP Scorcher
Multifilament (no wraps)

Bundles of micro synthetic fibers are twisted together, similar to natural gut. Nylon multifilaments are typically more comfortable than solid core strings due to the cushioning effect of hundreds or even thousands of micro fibers. Resultant effect is a soft and comfortable string, recommended for players suffering from arm problems who don’t want to pay the high price for natural gut. Normal use causes multifilament strings to fray, like gut, which can be alarming to players switching from solid core strings. With the exception of Kevlar and Zyex, multifilament strings are generally classified as “soft” strings.

Babolat X-Cel Premium
Gamma ESP
Head Fiber Gel
KLIP Excellerator
Prince Premier w/SoftFlex
Tecnifibre 515, NRG2, X-One BiPhase
Wilson Sensation, Sensation NXT
Multicore with Wraps

Smaller multifilament core with one or more outer multifilament wraps. Offers similar comfort benefits to multifilament strings with added durability.

Babolat Powergy
Gamma Live Wire
Head RIP Control

Designed to offer enhanced spin potential by wrapping an extra filament around the outer wraps or incorporating larger filaments into the outer wrap. Most effective texture string is Gamma Ruff. While officially a geometric string, Forten Kevlar Gear is included in our “Textured String” category and provides equal or greater spin potential as Gamma Ruff. Other examples include:

Gamma TNT Pro Plus Spin
Prince Topspin and Topspin Plus
Wilson Extreme Spin.

A combination of different materials blended together in an attempt to bring out the best features of each material. For simplicity, strings combining different grades of nylon, which are theoretically also composite strings, aren’t included in our list.

Gamma TNT Extreme Spin 19
TNT Fusion Plus
Head RIP Control, RIP Ti. Fibre, Ti. Fibre (coating)
Luxilon Big Banger, ALU-Power (polyester & fluorocarbon resin) Prince Perfection, Pro Blend (Duraflex), Synthetic Gut w/Duraflex, Topspin (Duraflex)

Monofilament Polyester

Durability-oriented monofilament string. All currently available monofilament strings are polyester. Good alternative to Kevlar hybrids because it’s less stiff but it has a dead feel and high initial tension loss. Recommended for frequent string breakers who don’t want to resort to Kevlar hybrids. String 3-5 lbs. higher than nylon to compensate for tension loss.

Babolat Pro Hurricane
Gosen Polylon
Kirschbaum Super Smash & Super Smash Spiky
Tecnifibre Polyspin.

Aramid Fiber Hybrids

Combines the strength and abrasion resistance of Kevlar mains with nylon (synthetic gut) crosses. Most durable of all string construction, but least “playable” due to Kevlar’s extremely stiff, dead feel. All current Kevlar string sets are hybrids, combining Kevlear mains and synthetic crosses.

Ashaway Crossfire 16 and 17
Forten Kevlar Gear and Thin Blend 18
Gamma TNT Fusion 19 and TNT Fusion Plus 16
Head Kevlar Blend 16
Prince Pro Blend Duraflex 16, Pro Blend Soft 16 and Pro Blend Spin 17
Wilson Hammer Last 16 and Hammer Last 19.


String tension is the final piece in the racquet-string-tension triad. It’s also the least understood by most recreational players. Let’s start with the basics – lower tensions provide more power, tighter tensions provide more control. This is a very general rule of thumb and assumes a certain level of player ability (especially the control part). A beginning player may need more control but tighter string tensions aren’t the solution. This player needs a soft, forgiving stringbed that lower tensions provide due to the frequency of off-center hits.Advanced players who swing fast and hit hard usually need more control and will, therefore, benefit from tighter tensions. There are, of course, always exceptions but these generalizations apply to the majority of players.

Each racquet has a recommended tension range. This range has been determined by the manufacturer as a result of extensive playtesting by real players. If a player doesn’t have a specific need (more power, arm problems, etc.), he should start at mid-range and make any adjustments from there.

Otherwise, here are some specific guidelines for selecting a string tension.

As we stated above, if a player is seeking more power from his racquet, he should try dropping tension a few pounds. The stringbed will deflect more (and the ball less), returning greater energy to the ball. There is a point of diminishing returns where the stringbed turns into a butterfly net, but it’s well below any racquet’s recommended tension range.

Control – a tighter stringbed deflects less and deforms the ball more, providing less energy than looser strings. This means the ball won’t fly as far when you hit it. Beginners who are shanking the ball in every direction won’t gain any advantage by increasing tension, but intermediate and advanced players who are hitting a lot of long balls will be able to reduce the depth of their shots without changing their swing. It is also generally accepted that spin potential is enhanced with higher tensions, which provides even more control for topspin and slice players.

Arm Injuries – lower tensions result in a softer stringbed and a larger sweetspot, reducing the amount of shock and vibration transmitted to the hand and elbow.

Switching Racquets – too many players are stuck on a tension (“I always string my racquet at 60 pounds”) and don’t make allowances when changing racquets. Whether changing head sizes, brands, or buying a new titanium racquet, a player will need to make the corresponding tension change. If 60 pounds was mid-range on his old racquet and the new racquet’s tension range is 50-60 pounds he should start at 55 pounds with the new racquet.

Switching Strings – if a player changes from a standard nylon or synthetic gut string to a kevlar composite or hybrid, we suggest he reduce tension to compensate for the added material stiffness. With composites, we recommend a 5% reduction. Kevlar hybrids should be strung 10% looser to approximate the same feel of nylon strings. On the other end of the spectrum, players switching from nylon strings to polyester may want to increase tension 5-10% to compensate for polyester’s high initial tension loss.

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