Tennis Glossary

Tennis Terminology Defined

Here is a list of some common technical (and non-technical) tennis terms you’ll find used on our site from time to time, along with their definitions. Please feel free to contact us at Tennis Express is you have any questions about them.

Racquet Terms:


Also referred to as “static balance”, it is the point where a racquet will actually balance on a beam or other instrument, and is not normally in the center of the frame’s length. If it is, that racquet is said to be “evenly balanced”. Most frames will fall into the other two categories: “head light”, with the majority of the weight in the handle, or “head heavy”, with the majority of the mass in the head. Balance can be expressed in three ways: inches or centimeters (measured from the butt of the racquet), or as “points” head heavy or head light (each point is 1/8” of length). Normally, heavier racquets will be balanced head light, while lighter ones will tend to be head heavy. Racquet balance can be altered with the placement of weight (usually lead tape) in the desired location, and can drastically affect racquet feel and performance.

Cross Section

Refers to the width of the racquet’s beams, and is an indicator of racquet stiffness and power. A racquet with wider beams will tend to flex less than one with more narrow beams (all else being equal), and as such will lose less energy to that flex and transfer more power to the ball. Cross section width is generally measured in millimeters, and is normally termed in the following groups: Player’s frames will generally have beam widths of 22mm or less; Tweener racquets will usually have beam widths of 23-27mm, and Game Improvement frames will tend to have the highest cross sections of 28mm and above.

Head Size

Refers to the actual strung area of the racquet’s head, and can be expressed in square inches or square centimeters. Head size is a determining factor in frame power and stability, as longer strings will have a higher “trampoline effect” (which can increase power). A wider head will have a larger “twistweight,” and will resist torque on off-center hits. A smaller head size can increase control (all else being equal), but will reduce sweet spot size, power, and torque resistance. There is no industry standard for head size classification, but a common range would be as follows:

Midsize: 85-95 square inches (550-615 square centimeters)

Mid Plus: 96-105 square inches (621-680 square centimeters)

Oversize: 106-115 square inches (686-744 square centimeters)

Super Oversize: 116 square inches and above (750+ square centimeters)

Grip Size

Refers to the circumference of the racquet handle. Most adult-size tennis racquets (27” and longer) available today have grip sizes ranging from 4 1/8”-4 5/8”.

American Size European Size
4" 0
4 1/8" 1
4 1/4" 2
4 3/8" 3
4 1/2" 4
4 5/8" 5


An indicator of how much effort is required to swing a racquet. Swingweight is a product of the racquet’s weight and balance point, and is expressed in kilograms of weight per square centimeter of balance, or kg/sq. cm. A higher swingweight will generally indicate a racquet that, while harder to swing quickly, will have a higher power level. A frame with a lower swingweight will have less power, but can be swung with more speed and less effort. Swingweight and mass are not necessarily the same, as a lightweight frame can have a head heavy balance point and thus a higher swingweight than a heavier frame with a head light balance. Swingweight can be increased by placing weight (usually lead tape) at any point above where the player holds the racquet (normally 10cm above the racquet’s butt). The only way to decrease swingweight is by removing something from the frame: bumper guard, grip or racquet paint. Reducing string gauge may have a minimal effect on swingweight.

Twist weight

A measurement of the frame’s torsional stability, or its ability to resist twisting in the player’s hand on off-center hits. Twistweight is a product of the frame’s weight and the width of the racquet head, and is expressed in kilograms of weight per square centimeter of width, or kg/sq. cm. Twistweight can only be increased by adding weight to the racquet (a racquet’s head cannot be made wider). The best place to add weight to increase twistweight would be at the widest point of the racquet head: the 3 and 9 o’clock positions. Larger-headed racquets will have a higher twistweight than smaller-headed ones of the same weight due to their wider hitting areas, and are recommended for players with arm injuries (there are other factors to be considered as well).

Recoil weight

A measurement of the frame’s ability to resist recoiling, or “kicking back” in the player’s hand, and is a primary factor in feel and stability on volleys. Recoil weight is a product of the racquet’s weight, balance and swingweight, and is greatly influenced by balance: more weight in the handle of the racquet will produce a higher recoil weight, and more mass in the head will reduce it. A high recoil weight frame will be heavy and very head light, like most modern players’ frames. Head size is not an influencing factor for recoil weight.

Trampoline Effect

The ability of the racquet strings to deform on ball impact, resulting in less energy loss and more stroke power, and is influenced by racquet head size, string tension and string construction. Larger-headed racquets (longer strings) will provide a higher trampoline effect than a smaller-headed version at the same string tension. Lower string tensions will generally increase the trampoline effect, as will strings with a higher level of elasticity.


Normally associated with a frame’s ability to reduce shock and vibration before it reaches the player’s hand, and is commonly associated with comfort and injury prevention. Frames can dampen shock and vibration by high levels of weight, low flex levels, longer string length (larger head size), narrower beam widths, or by manufacturer- installed dampening systems like Babolat Cortex, Wilson Amplifeel, or Pro-Kennex Kinetic technology. String vibration dampeners do not have a noticeable effect on dampening, but serve mostly to eliminate the sound (high-frequency vibrations) of the strings.

Sweet Spot

Refers to the area of the string face where the shot “feels” best, and the most power is generated, although there are actually three areas that could be called “sweet spots”. The Center of Percussion (COP) is the spot where the player will receive the smallest amount of shock as the ball is struck. The Node is the point where vibration is lowest, and the point of Maximum Coefficient of Restitution is the spot of maximum shot power, also being the lowest of the three “sweet spots” on the string face. These spots, while a product of the racquet’s weight, balance, length and head size, can be relocated with the application of weight (usually lead tape). By placing weight in the upper areas of the head, these spots can be raised, or they can be lowered by placing weight farther down on the racquet. String tension can also have an effect: lower tensions will increase sweet spot size, while higher ones will reduce it.


Refers to the process of altering a racquet to enhance or reduce certain playability characteristics. Most frame customization is done by adding weight (usually with lead tape, but melted silicone or hot glue could be injected into the handle) to various locations on the frame to increase power and/or stability. A frame can also be customized by changing handle size and/or shape with a heat-shrink sleeve, or by sanding a polyurethane foam handle to reduce its size. A butt cap can be changed or built up to give the player a more familiar feel if he’s changed brands of racquets.

Heat-Shrink Sleeve

A tube made of a material that forms around the racquet handle under application of heat to increase handle size. Heat-shrink sleeves are available in thicknesses to increase the handle by either ½ size (1/16”) or one full size (1/8”).

Tension Range

A range of string tension the manufacturer has recommended for maximum playability of the racquet for the majority of players. It can be expressed in pounds or kilograms. This range is where the racquet will play the best for the majority of players according to the manufacturer’s testing. Some players may find it necessary to string below or above this range, but care should be taken when exceeding it.

String Terms:


The application of force to the strings by a machine to achieve the desired playability of the player. Most modern racquets will be strung somewhere between 40-70 pounds (18-22 kilograms) of tension. There are two tensions for a tennis racquet’s strings: reference tension, or what the stringing machine is set at, and actual tension, or what is left in the racquet after the strings have stretched during installation. Actual tension can be measured with a specialized device such as a Beers ert300.

Elasticity: How quickly the string can recover to its original length after ball impact stretches it out. Strings with higher elasticity will tend to produce more powerful shots, and be more shock absorbent, as the string’s stretch also enables dispersion of vibrations. Elasticity is affected by string material, gauge, design and tension. A multifilament, polyurethane-based string of thin gauge, strung at a low tension, will be more elastic and resilient than a monofilament polyester-based string in a thicker gauge strung at a higher tension, for example.

Gauge: The diameter of the string, commonly expressed in millimeters and/or gauge numbers (the higher the gauge number, the thinner the string, and vice versa). There is no industry standard for string gauge, but a common range is as follows:

Gauge Size
15 gauge: 1.4-1.5mm
15L gauge: 1.35-1.4mm
16 gauge: 1.28-1.33mm
16L gauge: 1.22-1.28mm
17 gauge: 1.2-1.25mm
17L gauge: 1.15-1.22mm
18 gauge: 1.1-1.2mm

The overlap in the ranges allows for some confusion, as one company’s 17 gauge string, for example, could be the same diameter as another’s 16L: Luxilon ALU Power has a diameter of 1.25mm, for example, but is listed as 16L gauge, while Babolat RPM Blast also comes in a 1.25mm diameter, but is referred to as a 17 gauge string. Always shop for strings by their diameter, and you will make a more informed choice. Thinner strings (higher gauge numbers) tend to provide more power, feel and spin potential than a larger diameter (lower gauge number) string of the same type, although the thicker string will provide more control and durability.


The mixing of two different types or gauges of string in the same racquet. Hybrid stringing has become popular in the last several years due to the popularity of polyester-based strings. Since these strings are so stiff, many players have mixed them with synthetic or natural gut strings to make for a more playable and comfortable string job, while retaining much of the poly’s spin and durability characteristics.


A type of string design where numerous individual string filaments are wrapped or braided into a single length of string. Multifilament strings tend to produce more power and comfort than solid-core or multifilament strings, and are a preferred choice for players with arm problems. Examples of multifilament strings would be Tecnifibre X-One Biphase, Wilson NXT, Babolat Xcel, and Gamma Live Wire.


A type of string design where one string material, or a combination of them, is extruded, or drawn through a tube, to form a single piece of string. Monofilament strings tend to exhibit greater durability than solid-core or multifilament strings of the same material, but have less power, feel and comfort. Most modern polyester-based strings are of the monofilament variety. Examples of monofilament strings would be Luxilon ALU Power, Babolat RPM Blast, Prince Beast XP, and Tecnifibre Black Code.

Sold-Core String

A type of string design where a monofilament string (usually nylon) is used as a center core, then wrapped with one or more layers of filaments (also, usually nylon). Solid-core strings tend to exhibit playability characteristics somewhere in between monofilament and multifilament designs. Examples of solid-core strings would be Gamma TNT2, Prince Synthetic Gut, Gosen OG-Sheep Micro, and Babolat N.vy.

Natural Gut

A type of string design where individual strands of intestines (normally from cows) are processed and wrapped to make a length of string. Natural gut strings tend to provide the most resilient, powerful and comfortable strings available, and are the best recommendation for players with arm problems. The manufacturing process makes them the most expensive strings currently available. Examples of natural gut strings would be Babolat VS Team, Klip Armour Pro, Pacific Prime Gut and Wilson Natural Gut.


A very stiff, high-strength material used by players who are chronic string-breakers. Kevlar is normally used in the main (vertical) strings, and a synthetic string is used as the cross (horizontal) strings. Kevlar is very inelastic, providing high levels of control and durability but with very low levels of power and comfort. Examples of Kevlar strings would be Prince ProBlend and Ashaway Crossfire.

Main Strings

The strings that run vertically from the racquet head to throat. Main strings tend to be the “working strings” on the racquet, providing most of the power and spin, and also taking most of the workload. Most players will break a main string before a cross string.

Cross Strings

The strings that run horizontally across the width of the racquet head. Cross strings play more of a “supporting role” to the main strings, and as such will tend to break last.

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