Audio Compressor
A free online audio compressor that shrinks a file's size. Re-encode an MP3, WAV, M4A or FLAC to a smaller MP3 at the bitrate you choose, and see how much you saved. Runs in your browser with ffmpeg — your file is never uploaded.
How do I make an audio file smaller?
To shrink an audio file, load it here, pick a target bitrate — lower means a smaller file — and press Compress. The tool re-encodes the track to an MP3 at that bitrate and shows the before size, the after size and the percent saved. Use 64–96 kbps for voice and podcasts and 128–192 kbps for music; a lossless WAV or FLAC can drop 80–90% at 128 kbps. It reads almost any input (MP3, WAV, M4A, FLAC, Opus and more) and runs entirely on your device with ffmpeg compiled to WebAssembly, so nothing is uploaded. Need to cut it first? Use the MP3 Trimmer; to change format, the Audio Converter; to make it louder, the Volume Booster.
Frequently Asked Questions
How do I compress an audio file?
Load your audio file, choose a target bitrate — a lower bitrate means a smaller file — and press Compress. The tool re-encodes the audio to MP3 at that bitrate, shows you the old and new sizes and the percentage saved, and gives you the smaller file to download. Everything runs on your device, so nothing is uploaded. 128 kbps is a good default that roughly halves a typical 256 kbps song with little audible loss.
Will compressing reduce the audio quality?
Compressing to a lower bitrate is lossy, so some detail is discarded to save space. At 128 kbps and above the difference is inaudible for most speech and casual music listening; below about 96 kbps you may hear it on music, especially in cymbals and reverb. Pick the lowest bitrate that still sounds fine for your use — 64 to 96 kbps is plenty for voice and podcasts, 128 to 192 kbps for music.
How much smaller will my file get?
The size drop depends on the source. An uncompressed WAV or a lossless FLAC can shrink by 80 to 90 percent when re-encoded to a 128 kbps MP3. An MP3 that is already 320 kbps roughly halves when dropped to 128 kbps. A file that is already at or below your chosen bitrate will not get meaningfully smaller — re-compressing it only re-encodes it. The tool shows the exact before, after and percent saved after each run.
Is my audio uploaded, and what format do I get back?
Nothing is uploaded — compression runs entirely in your browser with ffmpeg compiled to WebAssembly, and the engine downloads once (about 10 MB) then later runs start instantly. The result is always an MP3 at the bitrate you chose, which plays everywhere; if you need a different format afterwards, run it through the Audio Converter. Your file and its compressed version never leave your device, so it works offline after that first load and there is nothing to sign up for.
Can I compress a voice recording for email?
Yes — compressing a voice recording for email is a common use. A long voice memo or interview recorded as a WAV can be many megabytes; compressing it to a 64 or 96 kbps MP3 makes it small enough to email or upload while staying perfectly clear for speech. Because the file never leaves your device, it is safe for private or confidential recordings.