Compress MP3

Shrink an MP3 by re-encoding it at a lower bitrate — in your browser.

Select an audio file

Re-encode an MP3 at a lower bitrate to shrink it — pick the bitrate below. Runs in your browser.

點擊選擇，或將檔案拖曳至此

如何 Compress MP3

1
Add your MP3
Drop in the file you want smaller.
2
Pick a bitrate
128 kbps for voice, 192 for a good default — lower bitrate, smaller file.
3
Compress and download
Click Compress; it's re-encoded in your browser.

How much smaller will it be?+

It depends on the original bitrate. Going from 320 to 128 kbps roughly halves the file; the tool shows the before/after size.

Is quality lost?+

Yes — re-encoding an MP3 at a lower bitrate discards more detail. 192 kbps is a good balance; 128 is fine for speech.

Is my file uploaded?+

No. It's decoded and re-encoded in your browser with a JavaScript LAME port.

Can I set a target size?+

Not directly here — pick the bitrate. Lower bitrate, smaller file.

你們會把我的檔案上傳到伺服器嗎？+

不會——這裡的每個工具都完全在你的裝置上處理檔案，不會向伺服器上傳任何內容。唯一的例外是 AI 工具，它們會把擷取的文字（而非檔案本身）傳送給 Claude 來完成工作。

有檔案大小限制嗎？+

我們沒有人為設下限制，但由於處理過程在你的瀏覽器中進行，非常大的檔案（超過 500MB 或 1000 頁）會受你裝置記憶體的限制，而非我們的限制。