Compress MP3 Online
Reduce MP3 file size directly in your browser. Choose the balance between file size and audio quality without uploading your file.
Drop your MP3 here
Compress MP3 audio locally without uploading to any server
or drop it here · up to 100 MiB / 20 minHow to compress an MP3 file
Reduce your MP3 file size in three quick steps right on your device.
- 01
Choose an MP3 file up to 100 MiB from your computer or phone.
- 02
Select a quality level (Smaller, Balanced, Better) or enter a target file size in MB.
- 03
Compress locally in your browser, preview the audio, and download the smaller MP3.
Understand MP3 bitrate and quality
Private, on-device audio compression
Your audio never leaves your computer or phone. All encoding runs locally in your browser using WebAssembly — no uploads, no cloud queues, and complete privacy.
Frequently Asked Questions
Up to 100 MiB and 20 minutes per file. Short recordings work best on phones.
How do I compress an MP3 file?
Select your MP3 file, pick your preferred compression level (96 kbps for maximum space saving, 128 kbps for balanced quality, or 192 kbps for higher fidelity), and click Compress MP3. You can listen to the preview immediately and download the compressed file.
Does compressing an MP3 reduce audio quality?
Yes. MP3 compression reduces file size by lowering the bitrate and discarding subtle audio details that the human ear is less sensitive to. For speech and podcasts, lower bitrates like 96 kbps sound very natural. For complex music, 128 kbps or 192 kbps preserves more detail.
What bitrate should I choose?
96 kbps is best for spoken word, lectures, and voice notes where file size is critical. 128 kbps is the recommended balanced option for everyday music and podcasts. 192 kbps is best when you want to preserve high-frequency acoustic detail from higher-bitrate sources.
Why is my compressed MP3 not much smaller than the original?
If your original MP3 was already encoded at a low bitrate (such as 96 kbps or 128 kbps), choosing an equivalent or higher bitrate will not reduce file size. ToAudio automatically detects your source bitrate and prevents wasteful re-encoding that would only increase file size without improving quality.
Can I compress an MP3 to a specific target file size (like 10 MB)?
Yes. Open “Target file size”, enter your desired size in megabytes, and ToAudio will automatically calculate the optimal bitrate needed to hit your target while respecting minimum acoustic limits.
Are my MP3 files uploaded to your servers?
No. All processing happens entirely inside your browser using client-side WebAssembly. Your audio files stay on your device and are never sent over the network.