Polyester vs Multifilament Tennis Strings — What's the Difference?

The short version

Polyester (co-poly): Durable, good for spin and control, harder on your arm, loses tension faster. Best for intermediate to advanced players with good technique and healthy arms.

Multifilament: Arm-friendly, lively feel, better power and comfort, less durable. Best for beginners, players with arm issues, or anyone who prioritises comfort over spin.

Polyester strings in detail

Polyester became the dominant string choice on tour in the early 2000s and completely transformed the game. Rafael Nadal's rise to dominance coincided with the widespread adoption of heavily textured co-poly strings that enabled extreme topspin.

TWU measures polyester strings with stiffness ratings typically ranging from 160–250 lb/in. This high stiffness means the string doesn't deflect much on contact — it snaps back quickly, which helps generate spin. But it also transmits more shock to the arm.

The other important TWU metric for polys is tension loss — how quickly the string goes dead after stringing. Most polyesters lose 15–50% of their tension within 24 hours of being strung, which is why touring pros restring before every match. For club players, this means your poly strings are likely playing dead even if they look fine.

Who should use polyester: Players who hit with significant topspin and need the string to "bite" the ball, players who break strings frequently, advanced players who want maximum control and spin.

Who should avoid it: Beginners, players with arm issues, seniors, players with compact swings who don't generate much racket head speed.

Multifilament strings in detail

Multifilament strings are made from hundreds or thousands of individual fibres bundled together, which gives them a soft, lively feel that's close to natural gut. TWU stiffness ratings sit between 100–160 lb/in — significantly softer than polyester.

The lower stiffness means more string deflection on impact, which translates to a trampoline-like feel and more natural power. You don't need to swing as hard to generate pace. Tension loss is also much lower — multifilament strings maintain their playability far longer than polyester.

The downsides: multifilament strings are less durable (they can fray and break more easily than polys), and they don't generate as much topspin for players who need it.

Who should use multifilament: Beginners learning to rally consistently, any player with arm pain or tennis elbow, seniors, players with compact swings, anyone who prioritises comfort over maximum spin.

What about natural gut?

Natural gut is the original tennis string and still the gold standard for feel and arm-friendliness. TWU stiffness ratings are in the 80–110 lb/in range — softer than any synthetic. It holds tension better than any other string type and provides exceptional power and comfort. The drawbacks: it's expensive (£35–50 per set), not ideal in wet conditions, and breaks more easily than polyester. Most tour pros use it as mains in a hybrid setup.

Hybrid stringing

Many players use a hybrid: polyester crosses paired with natural gut or multifilament mains. The gut/multi mains give you the arm-friendly, lively feel; the poly crosses add durability and some spin. This is the setup used by Novak Djokovic and many other tour players. It's an excellent compromise if you want spin without sacrificing comfort entirely.

The bottom line

If you're a recreational or club player who doesn't break strings monthly and doesn't have a fast, heavy swing — multifilament or a soft hybrid will likely serve you better than full polyester, and your arm will thank you. If you're an advanced player with heavy topspin who breaks strings every few weeks, polyester is the right choice — just be mindful of RA stiffness and go for softer options like Yonex Poly Tour Pro or HEAD Hawk Touch.