Why it matters
String tension is the single biggest variable in how your racket performs. Too high, too low, or unevenly decayed — each affects your accuracy, power and even your arm health. RacketTension puts that data in your pocket.
The science behind it
String tension directly controls the power, spin, and control you get from every shot. A racket strung at 25 kg plays completely differently to the same racket at 22 kg — even if both were strung by the same person on the same day.
What most players don't realise is that strings lose tension continuously from the moment they are strung. Within the first 24 hours, tension can drop by up to 10%. Over the following weeks and months, it continues to fall — often 20–30% lower than your requested pull tension within a few sessions.
Measuring your string tension lets you make informed decisions about when to restring, understand how your racket actually plays (not how you think it plays), and verify that your stringer hit the tension you asked for.
30%
Average tension drop in first 24h after stringing
2kg
Can change shot depth by 30–50 cm on groundstrokes
3×
More likely to restring at the right time with tracking
0
Extra hardware needed with RacketTension
Impact on your game
Loss of Accuracy
Lower tension creates a larger trampoline effect, making it harder to control where your shots land. Shots fly deeper and less predictably.
Reduced Power Control
Tension that's too high reduces the dwell time and power transfer, requiring you to swing harder for the same depth.
Arm & Elbow Injury
Overly tight strings transfer more vibration to your arm. Many cases of tennis elbow are aggravated by strings strung above the player's ideal tension.
Unnecessary Restringing
Without data, players guess when to restring — often too early or too late. Measuring tension tells you exactly when strings have dropped to an unplayable level.
Inconsistent Feel
If you play multiple rackets without checking tension, each may feel different. Measuring ensures all your rackets are matched to the same tension.
App capabilities
A complete string tension measurement and tracking tool in your pocket, backed by FFT signal processing — the same technology used in professional audio equipment.
Fast Fourier Transform analysis of string vibration frequency gives tension readings within 1–2 kg of professional tension meters.
Your phone's microphone captures the vibration. No Bluetooth sensors, no cables, no accessories — just your Android phone.
Pre-loaded with parameters for Luxilon Alu Power, Babolat RPM Blast, Head Hawk, Tecnifibre Black Code, Solinco Hyper-G and many more.
Enter your racket's head size, stringing pattern (16×19, 18×20, etc.) and string type for calibrated measurements unique to your racket.
Every measurement is logged with timestamp. Track how your strings degrade over days and weeks to optimise your restringing schedule.
Switch between kilograms and pounds in settings. Compatible with any string tension specification regardless of where your racket was strung.
Enter racket head size in square centimetres or square inches. The app converts automatically so you can use the spec printed on your frame.
Core measurement features are free. A subscription unlocks unlimited history storage and priority access to new string database entries.
Get started today
Available now on the Google Play Store for all Android devices running Android 6.0 or higher. Free to download and use.
Free to download — no credit card required
Works on most Android 6.0+ devices
No external hardware or accessories needed
Measurements saved securely to your account
Stop guessing
Download RacketTension free today and start measuring your string tension with nothing but your Android phone.