Compress MP3
Make an MP3 smaller by choosing a lower bitrate, with a clear before and after size.
MP3, WAV, M4A, FLAC, OGG, Opus, AIFF, WMA, AMR and the sound of most videos. Files stay on your device.
How it works
- Choose your MP3 files.
- Pick a bitrate; 128 kbps suits most music, 64 kbps suits speech.
- Click Compress and compare sizes.
- Download the smaller MP3 files.
How an MP3 gets smaller
MP3 size is bitrate times length, and the encoder here uses constant bitrate. A 3-minute song is about 4.3 MB at 192 kbps, 2.9 MB at 128 kbps and 1.4 MB at 64 kbps. The tool decodes your MP3 and encodes it again at the lower bitrate you choose, so it is a normal lossy re-encode: smaller, with a little more loss on top of the loss MP3 already has.
The Quality presets are 64, 128 and 192 kbps for stereo, and a lower value for mono. They never raise a file above the bitrate it already has, so a 96 kbps file stays at or below 96.
Speech, music and sample rates
For speech, mono at 48 to 64 kbps is clear and tiny. For music, 128 kbps stereo is a good balance and 192 kbps is close to transparent for most people. Under More options you can lower the sample rate to 32 or 22.05 kHz, which saves a little more and removes the highest frequencies. At rates below 32 kHz MP3 allows bitrates as low as 8 kbps.
The Target size mode finds the bitrate for you when you have a limit to meet. MP3 moves in fixed steps, so it may end a little under the size you asked for.
Questions
What bitrate should I pick?
64 kbps mono for speech and voice memos, 128 kbps for everyday music, 192 kbps when quality matters. Below 96 kbps stereo, music starts to sound thin.
Does compressing an MP3 twice make it worse?
Each re-encode loses a little more. One pass at a sensible bitrate is fine; avoid compressing the same file repeatedly, and keep the original.
Will tags and cover art survive?
Yes by default. Cover art can be large, so removing it under More options also saves space.
Is my audio uploaded?
No. Compression runs in your browser on your device. The only downloads are the page itself and, the first time you use a format, a small encoder file from this site.