MP3, M4A, FLAC, WAV or OPUS: choosing an audio format
2026-10-01
Audio formats fall into three groups. Which group a format belongs to tells you most of what you need to know.
| Group | Formats | What it means |
|---|---|---|
| Uncompressed | WAV, AIFF | Every sample is stored as-is. Largest files, no quality loss. |
| Lossless compressed | FLAC | Compressed like a zip file. Identical sound, roughly half the size of WAV. |
| Lossy | MP3, M4A/AAC, OGG, OPUS | Sound the ear is unlikely to notice is discarded. Much smaller files. |
Size per minute
Figures for stereo audio. CD-quality WAV is 16-bit at 44.1 kHz, which works out to 1,411 kbps.
| Format | Bitrate | Approx. size per minute |
|---|---|---|
| WAV / AIFF | 1,411 kbps | 10.6 MB |
| FLAC | varies with the music | 5–7 MB |
| MP3 or M4A | 256 kbps | 1.9 MB |
| MP3 or M4A | 192 kbps | 1.4 MB |
| MP3 or M4A | 128 kbps | 1.0 MB |
| OPUS | 64 kbps | 0.5 MB |
Which format for which job
- It has to play everywhere (car stereos, old players, any app): MP3.
- Apple devices, or the best quality for the size: M4A. At the same bitrate AAC generally sounds better than MP3.
- Voice messages, podcasts, streaming: OPUS. It stays intelligible at bitrates where MP3 falls apart.
- Archiving a music collection: FLAC. You can always make an MP3 from it later; the reverse is not true.
- Editing in an audio workstation: WAV, or AIFF on a Mac.
What converting cannot do
Two mistakes come up again and again.
- Lossy to lossless does not restore quality. Converting MP3 to WAV gives you a bigger file containing exactly the sound the MP3 already had. It is useful when a program only accepts WAV, not as a quality upgrade.
- Lossy to lossy loses a little more each time. Going from M4A to MP3 compresses already-compressed audio. Doing it once is fine. Avoid chains such as M4A → MP3 → OGG, and go back to the original file whenever you can.
Common conversions
- iPhone voice memo that will not open on Windows: M4A to MP3.
- Studio export that is too big to email: WAV to MP3.
- Lossless album for a player without FLAC support: FLAC to MP3.
- Shrinking a WAV archive without losing anything: WAV to FLAC.
The bitrates this site uses for each quality option are listed in the quality guide.
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