Many have asked me for a guide to string tension. The favorite question is, "What is a true 30lbs.?" There's no easy way to answer that but asfter so thought, a general comparison by sound would be the best (and easiest) way (while minimizing the variables). Remember, the higher the tension, the higher the pitch the string will make. For those that don't know, string tension can vary greatly due to string thickness, string type, the stringer, the stringing machine used, constant pull vs. crank, pre-stretching the string, weather changes, and time since stringing. Below is a general guideline based on sound with the variables minimized. Data: +All the rackets used were Yonex Ti10s +All were strung with Ashaway Micro Power White (0.70mm) *Note: DinkALot has since clarified that the string used was Ashaway ZGut X1709 (0.73-0.74mm) +All the rackets were strung with an electronic constant pull machine (www.tennishead.com) +All strings were pre-stretched 10% on each pull and clamped +All rackets were used for about 1 hour of play. Enjoy the video: http://www.youtube.com/watch?v=uISvZjI_V74 Disclaimer: your results may vary due to numerous factors. Testing the string sound right after you string your racket is always going to have a higher pitch. As time goes by and/or you play with your racket, the pitch will lower due to the string breaking down and most importantly losing tension. So you cannot compare a newly strung racket with one that has severely worn string.