Compress an audio file
Make a recording small enough to email, upload or fit on a phone. You choose the bitrate and see the estimated size before anything is encoded — no guessing, and nothing is uploaded.
- Processed on your device
- No upload, no waiting
- No signup, no watermark
How it works
Add your file
Any audio: MP3, WAV, M4A, AAC, OGG, FLAC or WMA. Its current bitrate and size are read straight away, so you know what you are starting from.
Choose how small
Pick a bitrate and the estimated size updates as you go. For speech, mono at 64–96 kbps is usually the right answer and can cut the size by ten times.
Download the smaller file
The result says exactly how much came off, and warns you if the settings could not actually make it smaller.
Frequently asked questions
How small can I make it without ruining it?
It depends entirely on what is in it. A single voice stays perfectly clear at 64 kbps mono, which is often a tenth of the original. Music needs 128 kbps at the very least and 192 kbps to be comfortable. Applause, rain and anything crowded needs more than you expect. Halve the bitrate, listen, and only go further if it still sounds right.
Why did my file not get smaller?
Because you asked for a bitrate at or above what it already has. Compressing a 128 kbps MP3 at 192 kbps makes a bigger file that sounds slightly worse — the extra bits are storing the first encoder's mistakes. The page shows the current bitrate and warns you when the setting cannot help.
Should I make it mono?
If it is one person speaking, yes — it halves the size and there is nothing in the second channel worth keeping. For music, interviews recorded with separate microphones, or anything where position matters, keep it stereo.
Does compressing twice make it worse?
Yes, and it is the most common way people quietly ruin a recording. Every lossy encode throws away more, and it never comes back. If you have the original WAV or the first recording, compress from that rather than from an MP3 you made earlier.
Is my file uploaded?
No. Everything is decoded and re-encoded by your own browser. A big file compresses as fast as your device can work, not as fast as your connection can upload — which is the whole point when the file was too big to upload in the first place.
What about a two-hour recording?
Fine. The output is written to the browser's own storage as it is encoded rather than held in memory, so length is limited by your disk rather than by the tab. Progress is shown and can be stopped at any point.
Good to know: Compression is lossy and cannot be undone — keep the original. A file already at a low bitrate has little left to give, and re-encoding it costs quality without saving much space.