Convert audio files
Re-encode MP3, WAV, FLAC, OGG, Opus, AAC and M4A, trim to the section you need, and set bitrate, sample rate and loudness.
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Accepts MP3, WAV, FLAC, OGG Vorbis, Opus, AAC, M4A. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
How audio conversion works here
Every conversion is a real re-encode
Audio is transcoded with ffmpeg using the reference encoder for each format: LAME for MP3, libopus for Opus, libvorbis for OGG, and FLAC or 16-bit PCM for the lossless targets.
Lossy targets default to 192 kbps, adjustable from 32 up to 512. That default sits just past the point where most listeners stop reliably hearing a difference on typical equipment. Lossless targets get no bitrate at all, because applying one to a lossless format would be a contradiction — the size follows the audio itself.
Converting between lossy formats costs a little each time
A lossy codec works by discarding what you are least likely to notice. Converting from one lossy format to another decodes the first and compresses again, so a second pass of loss lands on top of what was already gone.
Once is very hard to hear. It compounds, and a file converted repeatedly between formats is genuinely worse by the fourth generation. Convert from the best source you have rather than from a previous conversion, and going to a lossless format does not undo any of it — lossless preserves, it does not restore.
Two things that surprise people
Opus does not accept 44.1 kHz, the sample rate every CD-derived file carries, so audio converted to Opus is resampled to 48 kHz. That is a requirement of the codec rather than a setting, and it is not audible — but it explains why the resulting file reports a different rate from the one it came from.
Tag formats also differ between families. MP3 uses ID3, FLAC and OGG use Vorbis comments, and M4A uses MP4 atoms. Title, artist and album normally map across; unusual custom fields and occasionally embedded artwork have nowhere to go. Check the tags before deleting an original if your library depends on them.