You choose the bitrate
From 32 kbps for speech to 192 kbps for music. 128 kbps is the sweet spot: about a third of the size of a 320 kbps file, hard to tell apart on most speakers.
Reduce MP3 File Size
Make MP3 files smaller, right in your browser. Choose a bitrate, see the estimated size of each file before you start, and download the compressed MP3s. Up to 10 files at a time, and nothing is ever uploaded.
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Drop MP3 files here or click to choose
MP3, WAV, M4A, AAC, OGG, FLAC… · up to 10 files · max 200 MB each · the result is always MP3
Estimated sizes are based on the length of each file.
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Everything happens in your browser: your audio files are never uploaded.
Main features
An MP3 compressor that runs entirely on your device: smaller files, no upload, no waiting in a queue.
Size shown before you start
Every file in the list shows its estimated size at the chosen bitrate, so you can pick the setting that fits before compressing.
Mono for voice
Podcasts, lectures and audiobooks do not need stereo: one channel halves the size at the same bitrate.
Nothing is uploaded
FFmpeg runs inside your browser, so your files never leave your computer or phone.
Up to 10 files at once
Compress a whole batch with the same setting and download the results one by one or as a .zip.
MP3 in, MP3 out
WAV, FLAC, M4A, AAC, OGG and other audio files are accepted too and come out as MP3.
Never made worse for nothing
A file that is already at or below the target bitrate is kept as it is instead of being re-encoded for no gain.
Free, no account, no watermark
Compress as many files as you like. We only ask you to share the website if you find it useful.
Questions and answers
Is it really free?
Yes. There is no account, no limit on the number of files and no watermark. The website is supported by ads.
Are my MP3 files uploaded to a server?
No. Everything is processed by your browser with FFmpeg compiled to WebAssembly. You can even disconnect from the internet once the page has loaded.
Which bitrate should I choose?
For music, 128 kbps is the usual choice and 96 kbps is still acceptable on phone speakers or earbuds. For speech (podcasts, lectures, voice memos) 64 kbps is plenty and 32 to 48 kbps works if size matters most, especially combined with the mono option. Higher bitrates mainly make sense when the original is 256 or 320 kbps and you want to keep quality close to it.
Will the song sound worse?
A lower bitrate removes the quietest and highest-frequency details first. Going from 320 to 128 kbps is barely audible for most people; going below 96 kbps becomes noticeable on music, especially in cymbals and reverb. Speech tolerates much lower bitrates. The variable bitrate option spends bits where they matter and sounds better than a fixed bitrate of the same average size.
Why is my file not smaller?
MP3 size is almost entirely decided by bitrate × duration. If the file was already encoded at or below the bitrate you picked, there is nothing to gain and the tool keeps the original rather than lowering its quality. Choose a lower bitrate, or mono for voice recordings.
Which formats are supported?
MP3, WAV, M4A, AAC, OGG, OPUS, FLAC, WMA, AIFF and more. Whatever you put in, the result is an MP3 file.