Real Time Tension is calculated by measuring the vibration of the strings when you hit a tennis ball. It is different from the tension used to string a racket (Static Tension) mainly because Real Time Tension takes string stiffness into consideration while Static Tension does not.

On a freshly strung racket which is strung with 16-gauge string (the most common string thickness), Real Time Tension and Static Tension should be almost the same but for some players ‘almost’ is not good enough. In this case we offer a calibration tool which can make them exactly the same. Also, if you are not using 16-gauge string then calibration will probably be required if you want your display to match the number that the racket was strung at.

 

In order to calibrate, simply insert the calibration tool and rotate the dial until the display reads the correct number. The best time to do this is immediately after the racket has been re-strung. Note that different stringers will string rackets differently even if they are aiming for the same tension. We recommend that you find one stringer that you are happy with and only calibrate your RTT once. It is not necessary to re-calibrate unless you switch to a different type of string.