Tennis string packaging is full of technical-sounding terms. Some are useful, some are mostly marketing, and some tell you much more about the string than they first appear to.
Here’s what the most common terms actually mean — and what they can tell you about how a string will play.
Gauge
Gauge is the diameter of the string, measured in millimetres. Most tennis strings fall roughly between 1.15 and 1.35 mm.
As a general rule, thinner strings offer more feel, responsiveness, and spin potential, while thicker strings provide greater durability and a firmer response. 1.25 mm is a common middle-ground gauge, particularly for co-polyester.
You may also see US gauge numbers such as 16, 17, or 18. These work in the opposite direction: the higher the number, the thinner the string.
See our full guide to string gauge for more detail.
Construction
The construction tells you what the string is made of and how it is built.
Monofilament
A string with a single main strand or core. Most polyester and co-polyester strings are monofilaments. They are generally firm, control-oriented, and durable.
Polyester / co-polyester
Polyester monofilaments are designed primarily for control and spin. Modern co-polys often contain additional additives or polymers designed to improve characteristics such as feel, elasticity, or tension maintenance.
Multifilament
Hundreds or thousands of fine fibres bundled together. Multifilaments are designed to replicate some of the elasticity and feel of natural gut and are typically soft, powerful, and comfortable.
Synthetic gut
Usually a solid or composite core surrounded by one or more outer layers. Synthetic gut offers a balanced combination of power, comfort, control, and durability at a relatively accessible price.
Natural gut
Made from cow serosa. Natural gut remains the benchmark for feel, comfort, power, and tension stability, but comes at a higher price and requires more care.
Shape and coating
You’ll see terms such as shaped, twisted, textured, edged, and profiled on many modern strings. They all indicate that the string is not perfectly round.
A shaped string has edges or a specific profile designed to increase ball interaction and spin potential. The trade-off can be greater friction and wear, depending on the string and setup.
Slick or coated strings are designed to reduce friction and allow the strings to slide and return more easily. This can contribute to spin through snap-back and can be particularly useful in hybrid setups.
Colour
For most players, colour is mainly a matter of preference.
Different dyes and coatings can have a small effect on a string’s properties, but the difference is generally much less important than the string’s construction, gauge, and formulation.
If two versions of the same string are available, choose the colour you like.
What the pack doesn’t tell you
The packaging can tell you what the string is. It can’t tell you exactly how it will feel in your racquet.
Your racquet, tension, gauge, swing, technique, and playing style all affect the final result.
That’s where the Tennis Cube ratings and, ultimately, testing a set for yourself become important.
The best string isn’t the one with the best marketing. It’s the one that works best for your game.