MP3 Compressor
Reduce MP3 audio file size by choosing an output bitrate and compressing the audio directly in your browser.
Browser-based compression
Your MP3 is processed in your browser with FFmpeg WebAssembly. The selected audio file does not need to be uploaded to our server.
Large files may take longer
Compression uses your device CPU and memory. Processing speed depends on file length, device performance, browser resources, and the selected bitrate.
How to compress an MP3 file
Select your MP3
Choose the MP3 audio file you want to make smaller.
Choose a bitrate
Select a lower bitrate for a smaller file or a higher bitrate for more audio quality.
Compress and download
Run the browser-based compression and download your new MP3 file.
How MP3 compression works
MP3 file size is strongly affected by audio bitrate. A lower bitrate stores less audio data per second, which usually creates a smaller file but can also reduce sound quality.
This tool re-encodes the audio using the bitrate you choose. For speech, podcasts, voice notes, or casual sharing, lower bitrates may be sufficient. Music usually benefits from a higher bitrate.
Compression is performed in the browser using FFmpeg WebAssembly. Large or long audio files can take more time and may use significant memory on lower-powered devices.
Frequently asked questions
Which bitrate should I choose?
128 kbps is a useful balanced starting point. For spoken audio, 64 or 96 kbps may be enough. For music, 160 or 192 kbps generally retains more quality.
Will MP3 compression reduce quality?
It can. MP3 is a lossy audio format, so re-encoding at a lower bitrate may remove audio detail in exchange for a smaller file.
Why can the compressed file sometimes be larger?
If the source file already uses a lower bitrate than the output setting you choose, re-encoding can create a similar or larger file. Choose a lower bitrate and try again.
Is my MP3 uploaded to a server?
The selected MP3 is processed locally in the browser. The FFmpeg WebAssembly runtime is loaded when compression begins.
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