MP3 Compressor — Reduce an MP3 File’s Size, Online Free
Drop the bitrate, keep the file playable — shrink audio by up to 90% in your browser.
Drop an audio file, or click to browse
MP3, WAV, M4A, OGG, FLAC, and more
Processed locally — your file never leaves this tab
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Audio files are big because of their bitrate, and the honest way to shrink one is to re-encode it at a lower bitrate: a 320 kbps MP3 becomes a 128 kbps MP3 at about 40% of the size, and a heavy WAV becomes an MP3 at a tenth of its size. Pick the target, listen to the preview, and export — the encoding runs on your own device, so even long recordings finish in seconds.
Files worth shrinking
- Fit a lecture or voice memo under an email or chat-app size cap.
- Turn a WAV export into small MP3s for a quick review link.
- Take a 320 kbps library down to 128 kbps for a phone on mobile data.
How to use the Audio Compressor
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Drop your file
Add an MP3, WAV, M4A or other audio file. It is decoded on your device and never uploaded.
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Pick the target size
Lower bitrate, smaller file: 192 kbps for everyday music, 128 kbps still sounds fine to most ears, 64–96 kbps is ideal for speech.
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Listen and export
Preview the compressed result, then save it. Check that voices and cymbals still sound clean at the bitrate you chose.
This compressor shrinks the file, not the dynamics
Compress audio re-encodes at a lower MP3 bitrate. A 320 kbps file at 128 kbps is about 40 percent of the size. The quiet and loud parts stay in the same relationship.
Evening out a loud voice and a quiet one is the level compressor, a different page. That one does not make the file smaller.
Which bitrate to pick
The menu runs from 320 down to 64 kbps. Pick by what the file is:
- 192 or 320 kbps for music you will still listen to closely.
- 128 kbps for speech, a voice memo, or a copy you need to send.
- 64 or 96 kbps only when the destination is tiny and speech is enough.
What a second encode costs
Every pass throws away a little more. If the file is already 128 kbps, encoding it to 128 again does not help, and encoding it lower makes it duller.
Tags and artwork are not part of this shrink. If the MP3 is already small and you only need a new title or cover, use the MP3 tag editor, which copies the audio bytes unchanged.
Audio Compressor FAQ
How does audio compression work here?
The file is decoded and re-encoded as MP3 at the bitrate you pick. Size scales linearly with bitrate: one minute of stereo audio is about 2.4 MB at 320 kbps, 1 MB at 128 and 0.5 MB at 64.
Which bitrate keeps good quality?
192 kbps or 320 kbps for music you care about, 128 kbps for casual listening — most listeners cannot reliably tell it from 320 in a blind test. Speech and podcasts stay clear all the way down to 64–96 kbps.
Can compressing make the quality worse?
Yes, in one specific case: re-encoding an already-compressed MP3 at a much lower bitrate stacks a second lossy generation on the first. Compressing a WAV or FLAC source is cleaner — if you keep the original, you can always try a different bitrate again.
How small can I go?
64 kbps is the practical floor: about 0.5 MB per minute. Speech remains perfectly clear; music starts to sound dull and swishy. Below that, dedicated codecs like Opus do better than MP3.
Is my file uploaded anywhere?
No. Decoding and encoding both run inside your browser tab — you could disconnect from the internet after the page loads and compression would still work.
Will this even out loud and quiet parts?
No. This page only re-encodes at a lower bitrate so the file takes less space. To turn loud peaks down and bring quiet words up, use the level compressor. The bitrate stays whatever you pick on export there.
Does it work on my phone?
Yes. Pick the file and the conversion stays in the tab. Current Chrome, Edge, Firefox, and Safari on iPhone and Android decode the usual formats. A long file uses more memory, so a desktop is steadier past roughly an hour.
Related tools
WAV to MP3 Converter
Convert WAV files to MP3 in seconds — right in your browser, nothing uploaded.
Open WAV to MP3 Converter
FLAC to MP3 Converter
Convert FLAC files to MP3 in seconds — right in your browser, nothing uploaded.
Level Compressor
A broadband compressor that tames jumps in level — the peak of the file stays where it was.