What is a .mp3 file?
MPEG-1 Audio Layer III · Audio · Fraunhofer / MPEG · 1993
MP3 is the format that made digital music portable. Its lossy compression shrinks songs to a fraction of their original size while sounding good to most ears, and it plays on essentially every device ever made.
What is a .mp3 file used for?
MP3 discards audio detail that is hard to hear, which is how it makes files so small. At higher bitrates the loss is subtle, at low bitrates you can hear it.
Its unmatched compatibility is the reason it never really died. Every phone, car stereo, browser and player handles MP3.
For archival or critical listening, lossless formats like FLAC keep every bit, but at several times the file size.
What opens a .mp3 file?
The .mp3 format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Media Player
- VLC
- any browser
macOS
- Music
- QuickTime
- VLC
Linux
- VLC
- Rhythmbox
- mpv
Web
- Every browser
Open a .mp3 file step by step
- Confirm the file really is a .mp3. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Media Player or VLC.
- On Mac, use Music or QuickTime.
- On Linux, try VLC or Rhythmbox.
- Still stuck? Convert the .mp3 to WAV, which opens more widely.
Why can't I open my .mp3 file?
Almost always because no installed app understands MP3. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .mp3 at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .mp3 file
You can convert a .mp3 file to WAV, AAC, FLAC, M4A.
Audacity and FFmpeg both convert MP3. Converting MP3 to FLAC does not restore quality: the data MP3 discarded is gone, and the FLAC just stores the lossy result in a bigger file.
What is the .mp3 file signature (magic bytes)?
A .mp3 file starts with the hex bytes 49 44 33, which read as ID3 in ASCII. Programs identify MP3 by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for MP3. For a full breakdown, see the MP3 file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 49 44 33 | 0 | ID3 | 'ID3' tag at start |
| FF FB | 0 | - | MPEG frame sync (no tag) |
| FF F3 | 0 | - | MPEG frame sync |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .mp3 file?
MP3 is the format that made digital music portable. Its lossy compression shrinks songs to a fraction of their original size while sounding good to most ears, and it plays on essentially every device ever made.
Is MP3 or WAV better quality?
WAV is uncompressed and technically higher fidelity, but a high-bitrate MP3 sounds close to identical to most listeners at a tenth of the size.
What bitrate should I use for MP3?
320 kbps is near-transparent for music. 128 kbps is fine for speech and podcasts.
Comparisons
Related formats
Sources
Details on this page were checked against authoritative references. How sources are ranked and what is deliberately left out is set out in the methodology.