Compress an audio file
Re-encode an audio file as MP3 at a lower bitrate to cut file size, with a single bitrate slider.
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How it works
Re-encode an audio file as MP3 at a lower bitrate to cut file size, with a single bitrate slider.
Drop any audio file (MP3, WAV, M4A, OGG, FLAC). Set a target bitrate from 64 kbps (smallest, fine for voice) to 320 kbps (max MP3 quality). The tool runs the file through ffmpeg.wasm with libmp3lame, locally in your browser. For a 1-hour 320 kbps MP3, dropping to 128 kbps cuts the file from ~140 MB to ~55 MB with no audible difference for most listeners. For voice-only content (podcasts, lectures), 64-96 kbps is often enough. The progress bar tracks encoding. Output filename has -compressed.mp3 appended. For FLAC or WAV inputs, the size drop is dramatic since you're moving from lossless to lossy.
How to use it
- Drop your audio file. Lossless inputs like WAV and FLAC see the biggest size drops.
- Pick a bitrate. 128 kbps for music, 64-96 kbps for voice recordings and podcasts.
- Compress. ffmpeg.wasm re-encodes the file locally with libmp3lame; a progress bar tracks it.
- Download. The -compressed.mp3 downloads, often half the size or smaller.
Frequently asked questions
- What bitrate should I pick?
- 128 kbps is standard for music. 96 kbps for voice. 192 kbps if you have audiophile listeners. Going below 64 kbps starts to sound rough on music.
- Can I compress without losing quality?
- Not really. MP3 is lossy, going lower always loses something. For lossless compression, FLAC is the format, but the tool doesn't output FLAC.
- How much smaller will my file get?
- Depends on the source bitrate. Going from 320 to 128 kbps cuts file size roughly in half.
- Is my audio uploaded?
- No. ffmpeg.wasm runs in your browser, the file never leaves your device.