Tension calculator

Pick your frame and how you play. The proposal is calculated from the frame's verified head size, string pattern and stiffness, then adjusted for your style — and softened again if you mark the comfort setting.

How you play

Arm-sensitive or returning from injury Comfort first: elbow, wrist or shoulder history.

Tick this as well as your answer above — it works alongside the style you picked, not instead of it, and changes nothing unless it is marked. When it is on, the proposal comes back lower than the number for the same frame and style without it, and the string below switches to the softer one.

Your racquet

248 frames with verified specs

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The proposal

AI, from verified specs

For Babolat Boost Aero 2026 (260 g) · Heavy-spin baseliner

Recommended tension

21.5 kg 47.4 lb

Working range

21.0 – 22.0 kg

46.3 – 48.5 lb

18 kg23.5 kg29 kg

High confidence — this frame's specs are verified against the maker's own sheet.

Why this number

This frame carries no printed range, so we start at 23.5 kg — the middle of the ranges the makers do print, across the 151 frames here that have one.

A polyester is the stiffest material in the shop, and the printed range assumes nylon — so two kilos come off before anything else. This is the correction most club players miss.

The 16×19 pattern lets the mains slide and snap back, which needs no tension correction of its own.

Stiffness (RA) isn't on file for this frame yet, so there is no correction for it — the number above assumes an average layup.

The 102 in² head hands out free depth, so half a kilo more holds the length.

Heavy spin wants a bed that moves: half a kilo lower lets the mains slide and snap back, which is what puts the shape on the ball.

The string

Scored against this frame out of the 120 strings on file — family, shape, gauge and price. The number above is the tension for the first choice; a different family moves it, which is what the second card says.

First choice

Babolat RPM Blast 1.20 polyester · 1.20 mm · €11.90

A polyester is what lets the mains snap back, which is where the bite comes from.

Its octagonal profile is what bites the ball.

Babolat make both — the frame and the string were designed against each other and are sold as a pair.

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Alternative

Tecnifibre Triax 1.24 hybrid set · 1.24 mm

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Hybrid setup: Babolat RPM Blast 1.20 in the mains at 21.5 kg, a multifilament in the crosses at 22.0 kg.

Restring every 12 – 15 hours; a shaped string notches fast in the mains.

Indoor courts play faster: drop about 1 kg from the number above for the indoor season.