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Audio format

MP3 converter

An .mp3 file stores audio compressed with MPEG Audio Layer III, the codec that made digital music portable. By discarding sounds the human ear masks anyway, .mp3 shrinks a CD track to roughly a tenth of its original size, a trade-off that reshaped the entire music industry.

Private for supported formats — processed in your browser

Convert supported files

Runs on your device

Drop MP3 files here

Batch files can each use a different output. Nothing uploads for local conversions.

Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.

Where MP3 comes from

The codec emerged from research at Fraunhofer IIS and was standardized within MPEG-1 as ISO/IEC 11172-3 in 1993, with the .mp3 extension itself chosen in 1995. The last patents expired in 2017, making the world's most famous audio format finally license-free.

How MP3 works

  • Lossy perceptual coding built on a hybrid filterbank and psychoacoustic masking model
  • Bitrates run from 32 to 320 kbps, in constant or variable rate modes
  • Sample rates top out at 48 kHz with mono, stereo, or joint-stereo channels; there is no true multichannel mode
  • Each frame decodes independently, which is why streams can be cut, joined, and streamed so easily
  • Encoder quality varies meaningfully, with LAME's VBR presets long regarded as the reference

When to use MP3

  • Sharing music when the recipient's device is unknown
  • Distributing podcasts to the widest possible audience
  • Loading audio onto car stereos and older portable players
  • Extracting a video's soundtrack for casual listening

Strengths and limitations

Strengths

  • Plays on effectively every device made in the last twenty years
  • Small files with respectable quality at 192 kbps and above
  • Streams and seeks without any special server support
  • Completely free of patent restrictions today

Limitations

  • Artifacts such as pre-echo on sharp transients become audible at low bitrates
  • Less efficient than AAC or Opus at every bitrate
  • No lossless or multichannel option exists within the format

Compatibility

Every browser, operating system, phone, car stereo, and smart speaker of the modern era plays .mp3, making it the single safest audio format to hand to a stranger. Only antique hardware with narrow bitrate support ever struggles.

ID3v1 and ID3v2 tags carry title, artist, album, artwork, lyrics, and chapter frames; ID3v2.4 is the current revision.

Convert MP3 to another format

Convert other formats to MP3