The secret is as follows: the average racquet measures up to 27" in length. Stringing your racquet requires 38 feet of string. 38 feet translated to inches is around 456 inches. Measure the length of your racquet from the tip of the handle to the tip of the head 17 times. Add them all together and divide by 17. That's how many feet of string you will need. Here are some other useful tips when buying strings: the higher the tension, the faster the ball will go; the more durable the string, the longer it will last. Actually, that's simple math too! The best way to figure out what tension you need is with a digital or mechanical string gauge. These tools show you what string size you need at different tensions. Once you know the string size, simply look it up on our website to find out its recommended tension range. If you want to go beyond the recommended range, then do so. Just make sure you don't use strings that are too tight or too loose. Also, never tie a new string to an old one. This will cause the string to break. Now you should have enough information to buy yourself a new set of strings. Good luck and have fun playing tennis!