MP3 Format MP3 is one of the most widely used audio formats for ringtones. Its popularity stems from its efficient compression without compromising audio quality. This format is compatible with a vast majority of devices, especially those running on the Android operating system. M4R Format M4R is the default ringtone format for iPhones and iOS devices. This format is essentially an AAC file with a different extension. It supports advanced features like custom start and stop times, making it ideal for Apple devices. WAV Format WAV, or Waveform Audio File Format, is a high-quality, uncompressed audio format. While it provides excellent sound quality, it results in larger file sizes. Some Android devices and older cell phones support this format.