MP3 is the most widely supported audio format in the world. It was developed largely at Germany’s Fraunhofer Institute and standardised as part of MPEG-1 in 1993. Its patents expired in 2017, so it is now completely free to use. Every phone, computer, car stereo, smart speaker and audio app plays MP3.
How MP3 compression works
MP3 uses a model of human hearing, called psychoacoustics, to decide what can be thrown away. Quiet sounds masked by louder ones at similar frequencies, and very high frequencies most adults can’t hear, are stored with less detail or dropped. The result is typically 85–90% smaller than uncompressed audio while sounding very close to the original.
Bitrate
An MP3’s quality is mainly set by its bitrate: how many kilobits describe each second of sound.
| Bitrate | Typical use |
|---|---|
| 96–128 kbps | Speech, podcasts, audiobooks |
| 192 kbps | Music for everyday listening |
| 256–320 kbps | High-quality music |
320 kbps is the maximum. Files can be constant bitrate (CBR) or variable bitrate (VBR), which spends more bits on complex passages.
What MP3 is good at
- Compatibility. Plays practically everywhere.
- Small files. About 1.4 MB per minute at 192 kbps.
- Tags. ID3 tags store title, artist, album and cover art.
Where MP3 falls short
- Lossy. Detail removed during encoding can’t be recovered, and re-encoding an MP3 loses a little more each time.
- Efficiency. Newer formats such as AAC (in M4A files) and Opus sound as good at lower bitrates.
- Not for editing masters. Keep WAV or FLAC originals for editing and archiving.
MP3 and other formats
Convert to MP3 for sharing and compatibility: from WAV recordings, FLAC music, M4A voice memos, or the sound of a video. Convert MP3 to WAV when editing software or a device needs uncompressed audio, keeping in mind that it won’t restore lost quality.