Compress an audio file online
Shrink an audio file by lowering its bitrate, directly in your browser. Choose the quality and compare the before/after size.
or click to select it
Shrink an MP3, WAV, M4A, FLAC, AAC, OGG, OPUS or AIFF file by re-encoding it at a lower bitrate, directly in your browser — no installs, no uploads.
Re-encodes the audio as MP3 at the bitrate you choose. Bitrate is how much data is used per second of audio: a lower bitrate means fewer bits per second, so a smaller file, but with more audio detail thrown away; a higher bitrate keeps more detail at the cost of size.
Use cases
- Shrinking a long voice recording or podcast episode so it fits under an email attachment limit.
- Freeing up storage on a phone or old MP3 player with limited space.
- Turning a large WAV or FLAC recording into a small, easy-to-share file.
How it works
- 1
Upload your audio file
Works with MP3, WAV, M4A, FLAC, AAC, OGG, OPUS and AIFF.
- 2
Pick a quality level
Choose a lower bitrate for a smaller file, or a higher one to keep more quality.
- 3
Compare and download
See the original size next to the new one, with the percentage saved, before you download.
Technical details
Runs entirely on ffmpeg.wasm's libmp3lame encoder inside a Web Worker in your browser. If the source is already a lossy format like AAC or OGG, compressing it again means decoding it and re-encoding it as MP3 — a second round of lossy compression, so some quality loss is unavoidable; starting from a lossless source like WAV or FLAC avoids that extra loss.
Frequently asked questions
What bitrate should I use?
For spoken word (podcasts, voice memos), 64-96 kbps is usually plenty. For music, 128 kbps is a reasonable balance and 192-256 kbps is hard to tell apart from the original for most ears.
Will compressing an already-compressed file hurt quality?
Yes, a little. Re-encoding a lossy file like an existing MP3 or AAC discards additional detail on top of what the original encoding already removed. If you have access to the original lossless recording, compress that instead.