A quick guide to the most common audio formats - what they are, how they compare, and which one to use depending on what you're doing.
The most recognized audio format in the world. MP3 uses lossy compression to reduce file size significantly while keeping quality acceptable for most listeners. It's universally compatible - every device, media player, and platform supports it. The right choice for music libraries, podcasts, and general sharing.
The modern successor to MP3, and the default audio format used by Apple and most streaming services. AAC produces better sound quality than MP3 at the same file size. It's the audio codec inside most MP4 video files and iTunes purchases. A good choice when quality matters and compatibility with older hardware isn't a concern.
Uncompressed, lossless audio. WAV files store every sample exactly as recorded, resulting in perfect quality and large file sizes. Used in professional audio production, music recording, and any workflow where audio will be edited further. A 3-minute song is roughly 30 MB as WAV versus 4-7 MB as MP3 or AAC.
Unlike the formats above, a MIDI file (.mid) contains no actual audio - it stores instructions: which notes play, when, how hard, and on what instrument. That makes MIDI files tiny, but they need a synthesizer or sampler to turn into sound, and the same file can sound completely different depending on what plays it. Common as exports from notation software and DAWs. To hear a MIDI file or share it as real audio, convert MIDI to WAV - it renders the notes with a piano sampler in your browser.
For sharing or distributing audio, use MP3 or AAC - they're small and play everywhere. For recording or editing, use WAV to preserve full quality. If you're extracting audio from a video to edit it, WAV is the safest choice; if you just want to listen to it, MP3 is fine.
You can convert between MP3, AAC, and WAV - or extract audio from any video file - directly in your browser at FreeVideoTools.com. You can also render a MIDI file to WAV. No software to install, no upload required.