Tennis String Guide: Polyester vs. Multifilament vs. Natural Gut, and the Right Tension for You

Ask most recreational players what’s in their racket and you’ll often get a shrug. Maybe it’s whatever came pre-strung from the store. Maybe it’s whatever the pro shop recommended three years ago, and it’s still in there.

That’s a missed opportunity. Your strings are the only part of the racket that actually touches the ball. The type of string, its thickness, and the tension it’s strung at affect your power, control, spin, comfort, and feel, often as much as the racket itself. A $250 racket with the wrong strings can play worse than a $120 racket with the right ones.

The good news is that you don’t need to be a gear expert to get this right. This guide explains the main string types, how tension and gauge work, and how to choose a setup that fits your game and your arm.

Why Strings Matter More Than You Think

When the ball hits your racket, the string bed stretches, holds the ball for a few milliseconds, and sends it back out. How the strings behave during that moment shapes the shot:

• Power: how much energy the strings return to the ball
• Control: how predictable the ball’s direction and depth are
• Spin: how much the strings grip and “snap back” on the ball
• Comfort: how much shock and vibration reach your arm
• Feel: how much feedback you get on touch shots like volleys and drops
• Durability: how long the strings last before breaking
• Tension maintenance: how well the strings hold their original tension over time

No single string is best at all of these. Every string is a trade-off, and the right one depends on how you play.

The Main Types of Tennis Strings

Natural gut

What it is: The original tennis string, made from cow intestine (specifically the serosa layer) that’s twisted, dried, and coated. It’s been used for over a century and is still considered the benchmark for feel.

Best for: players who want maximum comfort and feel, players with arm sensitivity who can afford it, and all-court and serve-and-volley players.

Multifilament

What it is: A synthetic string made from hundreds or thousands of tiny fibers (usually nylon, polyurethane, or similar materials) bundled and wrapped together. It’s designed to imitate the feel of natural gut at a lower price.

Best for: beginners and intermediate players, players who want comfort, players with sensitive arms, and anyone who doesn’t break strings often.

Polyester (and co-polyester)

What it is: A stiff, durable monofilament string, a single solid strand rather than a bundle of fibers. Co-polyesters blend polyester with other materials to adjust stiffness and feel. Polyester strings have dominated professional tennis for years.

Best for: advanced players with fast, full swings who generate their own power, players who prioritize spin and control, and players willing to restring regularly.

Synthetic gut

What it is: A basic nylon string with a solid core and one or more outer wraps. It’s the simplest and most affordable option, and many rackets come pre-strung with it.

Best for: beginners, budget-conscious players, players still developing their strokes, and anyone who wants a simple, affordable starting point.

Hybrid setups

What it is: Two different strings in the same racket, one for the mains (vertical strings) and one for the crosses (horizontal strings). The most common hybrid pairs polyester with a softer string like multifilament or natural gut.

Common combinations:

• Polyester mains, multifilament or gut crosses: spin and control from the poly, with some added comfort and power
• Gut or multifilament mains, polyester crosses: more comfort and feel, with added durability and some spin. Roger Federer famously used a version of this (gut mains with poly crosses) for much of his career.

Best for: intermediate and advanced players who break strings often but want more comfort than full polyester, and players who want to experiment.

Other string types

• Kevlar/aramid: extremely durable but very stiff, usually used only in hybrids for chronic string breakers. Not recommended for players with arm concerns.
• Textured and shaped strings: polyester and synthetic strings with ridges, twists, or shaped profiles (pentagon, hexagon, and so on) designed to grip the ball for extra spin.

String Types at a Glance

Understanding String Gauge

Gauge refers to string thickness. Confusingly, a higher gauge number means a thinner string.

Thinner strings (17, 18):

• More feel and touch
• Slightly more spin potential and power
• Less durable, so they break sooner

Thicker strings (15L, 16):

• More durable
• Slightly less feel and spin
• Good for frequent string breakers

String Tension: The Most Misunderstood Setting

Tension is how tightly your strings are pulled when your racket is strung. Most rackets list a recommended range on the frame, typically somewhere around 50–60 lbs (about 23–27 kg).

The counterintuitive rule

Many players assume that tighter strings mean more power. It’s actually the opposite:

• Lower tension = more power, more comfort, and a higher launch angle. The strings stretch more and act like a trampoline, sending the ball off the racket with more energy.
• Higher tension = more control, less power, and a firmer feel. The string bed is stiffer, so the ball comes off with less energy and a more predictable trajectory.

How tension affects your game

Tension by string type

Because polyester is so stiff, most players string it lower than they would string a multifilament or synthetic gut, often about 10% lower. A player who strings multifilament at 55 lbs might string polyester around 48–50 lbs. Lower tension softens poly’s harsh feel and gives back some power. Hybrids often fall in between, and many stringers recommend stringing the polyester component a few pounds lower than the softer component.

Tension loss

All strings lose tension over time, starting the moment they come off the stringing machine. Natural gut holds tension best. Polyester loses it fastest, both in the first few hours and over the life of the string. That’s why polyester strings that haven’t broken can still feel “dead” and play inconsistently.

How Your Racket Affects Your String Choice

Your racket and strings work together. A few factors to keep in mind:

Head size: Larger heads (around 100–110 sq. in.) have longer strings and a bigger sweet spot, which produces more power. Smaller heads (around 95–98 sq. in.) offer more control.

String pattern:

• Open patterns (for example 16×19): more spin and power, but strings may break sooner
• Dense patterns (for example 18×20): more control and durability, but less spin

Frame stiffness: A stiff racket paired with stiff polyester at high tension can be harsh. If your racket is on the stiffer side, consider a softer string or lower tension.

Matching Strings to Your Playing Style

Here are some common player types and setups to consider as a starting point:

The beginner or developing player

• String: synthetic gut or multifilament
• Gauge: 16
• Tension: middle of the racket’s recommended range
• Why: affordable, forgiving, comfortable, and gives easy power while you develop your strokes

The recreational player who wants comfort

• String: multifilament, or natural gut if the budget allows
• Gauge: 16
• Tension: low to middle of the range
• Why: maximum comfort and feel without sacrificing too much control

The intermediate player who breaks strings

• String: hybrid (polyester mains with multifilament crosses) or a thicker-gauge multifilament
• Gauge: 16
• Tension: middle of the range, with the poly a few pounds lower
• Why: improves durability while keeping comfort

The advanced, topspin-heavy player

• String: polyester or co-polyester
• Gauge: 16L or 17
• Tension: low to middle of the range
• Why: maximum spin and control for fast swings. This works best if you restring regularly.

The all-court or serve-and-volley player

• String: natural gut or a gut/poly hybrid
• Gauge: 16
• Tension: middle of the range
• Why: excellent feel at the net, with some control for groundstrokes

The player with arm, elbow, or shoulder concerns

• String: multifilament or natural gut
• Gauge: 16
• Tension: low end of the range
• Why: reduces stiffness and shock

How Often Should You Restring?

The classic rule of thumb

Restring your racket as many times per year as you play per week. If you play three times a week, restring about three times a year.

This rule works reasonably well for synthetic gut, multifilament, and natural gut. It doesn’t work well for polyester, which loses playability much faster.

Polyester players

If you play with polyester, consider restringing based on hours played, not just breakage. Many players and stringers suggest replacing poly after roughly 15–25 hours of play, or when you notice:

• Less spin and control
• The ball flying long or feeling unpredictable
• A harsh, “boardy” feel
• Strings that stay out of place and don’t snap back after shots

Signs any string needs replacing

• Visible fraying, notching, or wear
• Strings that move around and stay out of position
• A noticeable loss of feel, control, or power
• Increased arm discomfort
• It’s been months and you can’t remember the last restring

Working with a Stringer

A good stringer can make a big difference to how your racket plays. When you drop off your racket, be ready to tell them:

• What string you want, or ask for a recommendation
• What tension you want, in lbs or kg
• Your playing style and level
• Any arm discomfort
• What you liked or didn’t like about your last setup

Questions to ask

• “What tension would you recommend for this string in my racket?” A good stringer knows how different strings play at different tensions.
• “Do you pre-stretch strings?” Some strings, especially natural gut and some multifilaments, benefit from pre-stretching.
• “What kind of machine do you use?” Electronic constant-pull machines are generally the most consistent, though experienced stringers can get great results on other machine types.
• “How long will it take, and what will it cost?” Labor typically runs $15–$30, depending on your area and the turnaround time.

Common String Mistakes to Avoid

• Copying the pros. Most pros use polyester at specific tensions, and they restring constantly. Their setup was built for their swing, not yours.
• Leaving polyester in too long. Polyester often plays poorly long before it breaks. Dead poly is uncomfortable and inconsistent.
• Stringing too tight for control. Very high tension can reduce power and comfort. If you’re struggling with control, technique or string type may be the issue.
• Never restringing. Factory strings in a racket you’ve had for two years aren’t helping you.
• Ignoring your arm. If your elbow or shoulder bothers you, look at your string type and tension, and talk to a coach and a medical professional.
• Changing too many things at once. Change one variable at a time (string type, gauge, or tension) so you know what made the difference.

Quick-Start Recommendations

Still not sure where to start? Use this as a simple guide:

These are starting points, not rules. The best setup is the one that feels good and helps you play your best.