Audio Tools
MP3 Compressor
Reduce MP3 file size while balancing audio quality and file size. 100% client-side — your file never leaves your device.
Runs entirely in your browser — your audio never leaves this device
Private & client-side
Your MP3 is decoded and re-encoded at a lower bitrate locally in your browser. Files are not uploaded to our servers.
Drop your audio file here
or click to choose from your device
Choose Audio FileHow MP3 compression works
An MP3’s size depends mostly on its bitrate — the amount of data used for each second of audio. A song at 320 kbps uses about 2.4 MB per minute; at 128 kbps it uses under 1 MB. Re-encoding at a lower bitrate is the simplest way to make an MP3 smaller for email, messaging apps, websites or devices with limited storage.
The MP3 Compressor decodes your file and encodes it again at the bitrate you choose, entirely inside your browser.
Common uses
Email attachments
Fit long recordings within attachment limits.
Messaging apps
Send audio that uploads quickly on mobile data.
Websites and e-learning
Reduce bandwidth and loading time for audio lessons.
Storage
Save space on phones, MP3 players and memory cards.
Recommended bitrates
Spoken word such as podcasts, lectures and audiobooks sounds fine at 64–96 kbps. Music needs at least 128 kbps, and 192 kbps keeps good quality while still saving space compared with 320 kbps.
Quality cannot be regained
Compression permanently removes audio detail. Compress a copy and keep the original file if you may need full quality later.
Questions
Frequently asked questions
Is the MP3 compressor free?
Yes. It is completely free, with no sign-up and no limits.
Are my audio files uploaded to a server?
No. Your MP3 is decoded and re-encoded at a lower bitrate entirely in your browser. The file never leaves your device.
Is MP3 compression lossless?
No. MP3 is a lossy format, so re-encoding at a lower bitrate reduces file size by discarding more audio data. The trade-off is between smaller size and lower quality — lower bitrates mean smaller files but reduced fidelity.
Which bitrate should I choose?
For speech, 64–96 kbps is usually enough. For music, 128 kbps is a reasonable minimum and 192 kbps keeps good quality while still saving space.