MP3, WAV or FLAC: which audio format should you use?

MP3 is lossy: it removes sounds you are unlikely to hear, which is how it gets files a tenth of the size or less. WAV is uncompressed: exact, but about 10 MB per minute in stereo at CD quality. FLAC is lossless: it compresses the audio without throwing anything away, and decodes back to exactly the same sound as the WAV.

We took a 3-minute-52-second song as a CD-quality WAV of 40.9 MB and converted it with this site's converters. The MP3 at the default 128 kbps took 3.7 MB, 9% of the WAV; even the highest MP3 setting, 320 kbps, stayed under a quarter.

FLAC came out unusually small, at 35%. Our test song had already been compressed once before we made the WAV, and that leaves less fine detail to store. FLAC copies of CD audio are usually around half to two-thirds the size of the WAV.

For listening and sharing, use MP3: it plays on every device, and at 192–320 kbps most people find it very hard to tell from the original. For editing, mixing and transcription, use WAV: every program accepts it and editing it adds no losses. For archiving a music collection or important recordings, use FLAC: perfect quality in less space, with proper tags for title, artist and album.

128 kbps, the default, is plenty for speech: podcasts, lectures, voice notes. For music, 192 kbps is a good everyday choice at about 1.4 MB per minute. Choose 320 kbps when space does not matter and you want the best an MP3 can do; it costs two and a half times the space of 128. You will find the setting under Advanced options as Audio quality.

You can always go from lossless to lossy, never back. We converted our 3.7 MB MP3 back to WAV: the file grew to 40.9 MB, exactly the size of the original WAV, but it still sounds like the MP3, because what the MP3 removed is gone. Turned into FLAC it even reached 29.7 MB. Keep a WAV or FLAC master and make MP3 copies from it.

The song is "I Don't Know" by Jenyfa Duncan, from the Free Culture Showcase that ships with Ubuntu, decoded to a CD-quality WAV (44.1 kHz, 16-bit stereo). Every conversion used this site's converters with default settings unless the table says otherwise, through the same FFmpeg commands that run on our servers. Music with more detail, such as a classical recording ripped from a CD, gives larger FLAC files; MP3 sizes depend only on the bitrate and the length.