Audio File Compressor
Shrink audio file size by re-encoding at a lower bitrate without losing clarity. Free, no signup, works in your browser.
Everything runs inside your browser — your file is never uploaded to a server.
First run downloads the media engine (~30 MB) once, then it stays cached.
About this tool
Large audio files are slow to upload, share, and store, especially recordings exported at high bitrates that far exceed what most listeners can perceive. This compressor re-encodes your audio at a lower, configurable bitrate, dramatically shrinking file size while keeping speech and music intelligible. It runs on FFmpeg compiled to WebAssembly, so the encoding happens entirely on your device's CPU using efficient codecs like MP3 or AAC. You can pick a bitrate that balances quality and size depending on whether the content is spoken word, which tolerates lower bitrates well, or music, which benefits from higher ones. Preview the estimated output size before running the full compression, then download a file that's often a fraction of the original size, ready for email attachments, messaging apps, or slow connections.
How to use this tool
1. Choose your audio file
Select the audio file you want to shrink from your device.
2. Pick a target bitrate
Choose a lower bitrate suited for voice or music content.
3. Run the compression
FFmpeg re-encodes the file locally at the chosen bitrate.
4. Download the smaller file
Save the compressed audio, ready for sharing.
Why use this tool
Uncompressed or high-bitrate audio files are often far larger than necessary for casual listening, making them cumbersome to email or upload. Re-encoding at a leaner bitrate keeps content clear while cutting file size dramatically, all processed locally so no file ever needs to leave your device before you're ready to share it.
Tips & best practices
- For podcasts and voice memos, 64-96 kbps mono keeps files small without sacrificing intelligibility.
- For music you want to archive with better fidelity, stick to 192 kbps or higher.
- Combine with the mono converter first if the source is stereo but the content is spoken word, cutting size even further.
Common use cases
- Shrinking a podcast recording before uploading it to a hosting platform.
- Compressing voice memos so they fit within email attachment limits.
- Reducing music file sizes for a mobile device with limited storage.
- Preparing audio files for faster upload to transcription services.
- Making a large voice recording small enough to send over WhatsApp.
Frequently asked questions
What bitrate should I choose for voice recordings?
64-96 kbps is usually enough for clear speech while cutting file size significantly.
Will compressing reduce audio quality?
Some quality loss is inherent to lower bitrates, but at reasonable settings it's rarely noticeable for speech.
Which output formats are available?
MP3 and AAC are the most common choices for compact, widely compatible output.
Can I compress music without losing too much fidelity?
Yes, using 128-192 kbps keeps most music sounding close to the original.
Does file length affect compression time?
Yes, longer files take proportionally longer since encoding happens on your device's CPU.
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