Converting Audio Without Uploading It
Audio files change format constantly: a voice memo that a transcription service will not accept, a lecture recording in a format an old car stereo cannot read, a WAV export that is far too large to email. The conversion itself is unremarkable, the awkward part is that most online converters want the recording first.
This converter runs on your own machine using the audio codecs already built into the browser, so a private recording stays private.
How to Convert an Audio File
Two settings decide the outcome: the target format and the bitrate.
- Drop the audio or video file onto the box above. Audio can be extracted from video files as well.
- Choose the output format. M4A carries AAC, which is efficient and plays everywhere; WAV is uncompressed and lossless.
- Set the bitrate. 128 kbps is ample for speech, 192 to 256 kbps suits music.
- Read the resulting size before downloading, particularly if you chose WAV, which will be much larger than the input.
- Download the converted file. The original is untouched.
- For a file that has to be a specific format for a particular device or service, check what that service actually accepts before converting, the requirement is often looser than it appears.
Lossy, Lossless and Generational Loss
AAC and MP3 are lossy: they discard sound the ear is unlikely to notice and reconstruct an approximation on playback. WAV and FLAC are lossless, storing the waveform exactly. That distinction matters most when a file will be re-encoded, because each lossy generation discards more than the last.
Converting a 128 kbps file up to 256 kbps does not improve it. The information removed by the first encoder is gone, and the higher bitrate simply stores the degraded audio more faithfully, in a larger file. Always convert from the highest-quality source available rather than from a copy that has already been through a lossy encoder.
Formats and What They Are For
The common audio formats and where each earns its place.
| Format | Type | Typical size, 3 min | Best for |
|---|---|---|---|
| WAV | Uncompressed | ~30 MB | Editing, mastering, archival |
| FLAC | Lossless compressed | ~18 MB | Archival at half the size of WAV |
| AAC (M4A) | Lossy | ~4 MB at 192 kbps | General use, Apple ecosystem |
| MP3 | Lossy | ~4 MB at 192 kbps | Maximum compatibility, older devices |
| Opus | Lossy | ~2 MB at 96 kbps | Voice and streaming, best efficiency |
| OGG Vorbis | Lossy | ~4 MB | Open format, games and web |
Opus is technically the strongest of the lossy formats and noticeably better than MP3 at low bitrates, but MP3 remains the safest choice for old hardware. Format support in a browser depends on the browser, so the options offered here may be narrower than this list.
Choosing a Bitrate
Bitrate is the main quality control in a lossy format, and the useful range is narrower than people assume. For spoken word, 96 to 128 kbps is transparent, going higher adds file size and nothing audible. For music, 192 kbps is good and 256 kbps is where most listeners stop being able to tell it from the source on ordinary equipment.
Above that the returns fall away sharply. A 320 kbps file is roughly a quarter larger than 256 kbps for a difference few people can identify in a blind comparison. If the goal is genuine fidelity rather than a high number, a lossless format is the honest answer and a higher lossy bitrate is not.