
Ever since cellphones became popular, everyone has wanted to personalize their ringtones. The generic, instrumental tones that come preloaded on most phones just won't do the trick. Now it's even possible to assign individual ringtones to each saved contact, making ringtones a sort of auditory caller ID. And since new songs are always coming out, the world's library of ringtones is constantly growing.
Ringtones have become a billion-dollar business, with the musical files costing only as much as any other song on the Internet. Since MP3s are digital music files, they can easily be converted into ringtones for little to no cost at all!
There are two main ways to convert MP3s: manual conversion through sound-editing software and automatic conversion through an online service. Editing files on your own adds more control, but it takes a little more work.

A simple Internet search for "MP3 editor" will give you a link to free MP3 editor software. Once the software is downloaded, simply open up your desired song and crop 15 to 25 seconds of a song. Save it, connect your phone to your computer through a cable or Bluetooth, and move the shortened file over. If you want to create ringtone for iPhone then you need ringtone creator with M4R support and iTunes to upload ringtone.
Using an Internet service is sometimes easier, but it can cost a little money. All such services require is a phone number and an MP3. You upload the file, and the new ringtone file is sent to your phone in a text message. These services will sometimes even convert entire songs. Converting an MP3 into a ringtone has become just that easy!