Which tennis string gauge should you choose?

In short: gauge refers to a string's diameter. The thinner it is, the more comfort, power and bite on the ball it offers — but the shorter it lasts. The thicker it is, the longer it lasts, with a slight trade-off on comfort and spin. Most players sit around 16 to 17 gauge.

Understanding gauge numbers and millimetres

Gauge is expressed either in millimetres or in US gauge numbers (15, 16, 17, 18...), with a reversed logic that often causes confusion — the higher the number, the thinner the string. Gauge 16 (around 1.30 mm) is the most popular all-round choice; exact mm-to-number mapping can vary slightly by brand.

Thin vs. thick gauge: the real effects

A thinner string flexes more easily on impact: it bites the ball more, favouring spin (topspin, slice) and giving a sense of extra power and comfort. In return, it wears and breaks faster, especially for players who hit hard or play often. A thicker string resists wear and breaking better, at the cost of a slightly duller feel and reduced spin potential.

Which gauge fits your profile?

• Beginner or recreational player: gauge 17 (around 1.25 mm / 0.049 in) offers a good balance of comfort and power without sacrificing too much durability.
• Regular player: gauge 16 (around 1.30 mm) remains the most practical all-round choice if you don't break strings too often.
• Competitive player or frequent string-breaker: gauge 15L or 15 (around 1.35 mm+) favours durability and control, at some cost to feel.
• Player chasing spin and feel above all: a thin gauge (17L or 18, under 1.20 mm) maximises bite on the ball, accepting a shorter lifespan.

Gauge works together with the string you choose

See our article on which string to choose for the full family overview, and our comparison of monofilament vs. multifilament for that specific trade-off.