MP3 Compressor
Drop the bitrate to hit a target file size for email or upload limits.
Drop files, or click to browse
MP3, WAV, and other audio files welcome
Frequently asked questions
What bitrate should I pick?+
128 kbps is a good balance for speech and casual listening; 192–320 kbps preserves more detail for music.
Is my file uploaded to a server?+
No — compression runs locally using your browser's own built-in media codecs, in your browser tab.
Is there a maximum file size?+
There's no fixed file-size limit since nothing is uploaded to a server. Processing time scales with the track's length rather than a hard cutoff.
How do I compress a MP3?+
Drop your MP3 into the box above and pick a bitrate — a smaller file is ready to download as soon as encoding finishes.
About MP3
What is MP3?
MP3 is the format that made digital music mainstream — lossy compression that plays back on essentially every device made in the last 25 years.
Full MP3 format guide →Full-size MP3 exports are often much larger than they need to be for how they're actually used. Compression finds a smaller file size that still looks (or sounds) right for the screen, feed, or inbox it's headed to.
How it works
- 1
Drop your file in
Drag your audio onto the box above, or click it to browse — there's no account to create and no upload to wait on.
- 2
Adjust the slider
Drag the quality slider and watch the estimated file size update in real time.
- 3
Download the result
Your browser processes everything locally and hands you a download link the moment it's done — nothing was ever sent to a server.
Is it private?
Everything happens locally, inside this browser tab. Your audio is read from disk, processed with WebAssembly running on your own device, and handed back to you as a download — it's never transmitted anywhere, so there's nothing to intercept and nothing stored on a server.
Common use cases
- Music libraries
- Podcasts
- Prepping a podcast episode for a hosting platform
- Fitting a voice memo under a messaging app's size limit
Supported formats
This is one of many pairings the audio toolkit handles. In total it covers:
Other compressors
Format details
About MP3 files+
MP3 is the format that made digital music mainstream — lossy compression that plays back on essentially every device made in the last 25 years.
MP3 (MPEG-1 Audio Layer III) was developed by the Fraunhofer Institute and standardized as part of MPEG in the early 1990s, and it became the format that made portable digital music practical in the first place — shrinking a CD-quality track down to roughly a tenth of its uncompressed size by discarding audio detail the human ear is least sensitive to. Decades later, despite the rise of more efficient codecs like AAC and Opus, MP3 remains the safest choice whenever compatibility is the priority, since there's essentially no device or piece of software made in the last two decades that can't play it.
How to open a MP3 file
Opens readily in Any media player, Any web browser, Every phone and car stereo made in the last two decades. For real editing, use Audacity (free), Adobe Audition.
Good for
- universal playback support
- small files at a reasonable bitrate
Watch out for
- lossy — some audio detail is discarded permanently
Need another format? Try the full Audio Compressor, or explore all audio tools.