MP3 is by far the most popular modern audio format in use today. AudioFormat has created a very simple to use and yet full featured MP3 converter that is totally free to use and 100% web based. Just browse and upload your mp3 file and choose the output format you wish to convert it to, as well as the final quality anywhere from 320 kbps down to 64 kbps. The lower the kbps the smaller the file size. Smaller mp3s allow you to put more files on devices like mp3 players, but there is trade off in that the audio quality will be reduced.