Audio File Compressor

Audio file compression and audio dynamic-range compression are two completely different things. This tool does the first one — making the file smaller on disk, typically by lowering the bitrate or switching to a more efficient codec. It does NOT do the second (the studio effect that levels out loud and quiet parts).

When you compress an MP3 from 320 kbps to 128 kbps, FFmpeg re-encodes the audio at the lower bitrate. The encoder discards more frequency information using its psychoacoustic model — sounds it predicts you won't notice. Lower bitrate = smaller file = some quality loss. The trade-off is honest, but 128 kbps MP3 is good enough for most everyday listening on phones and laptops.

Lossy formats (MP3, AAC, OGG, Opus, M4A) compress by discarding inaudible audio data — they're already small relative to lossless. Re-encoding at a lower bitrate makes them smaller still. Lossless formats (WAV, FLAC, AIFF) preserve every sample and don't have a 'bitrate' the same way. WAV is uncompressed PCM; FLAC compresses but losslessly.

For lossless files, this compressor re-encodes within the same lossless container. That gives modest savings only — typically 0–10% for FLAC, none for WAV. If you want dramatic file-size reduction from a WAV or FLAC source, the right move is converting to a lossy format like MP3 or Opus instead — see our format-specific tools.

Most online compressors upload your file to their servers, process it there, and stream the result back. That's a privacy hit you don't always need. This tool runs the entire compression pipeline in your browser using FFmpeg compiled to WebAssembly. The file never crosses the network. We don't see your audio, can't store it, and have no way to recover it. This matters if you're compressing client recordings, voice memos, sensitive interviews, or anything else you'd rather not hand to a third party.

If you're trying to fit a long recording into a tight upload limit (Discord 25 MB, WhatsApp 16–100 MB, Gmail 25 MB attachment), compression usually solves it. But if quality actually matters (mastering source, archival recording, court audio, anything that might be analyzed forensically), keep the original. Lossy compression is one-way — once you've encoded at 64 kbps, you can't recover the discarded audio data by decompressing back to WAV. Always keep the source.