The best indication that it’s time to change your strings (besides the obvious one of them breaking!) is the amount of tension they’ve lost. Racquets gradually lose tension over time (the rate of tension loss depends on the type of string). Eventually, the strings will lose their resiliency which results in a loss of control and power.

Take the guess work out of noticing loss of tension by using the string meter. By getting a base reading right after your racquet has been strung you can compare the tension over the following weeks.