Online Tool Store
Audio Converter
Convert audio between MP3, WAV, OGG, FLAC, and M4A with sample rate and mono/stereo channel control, right in your browser — nothing is uploaded.
This works right here on your device — nothing gets sent out.
Loading the sample audio — choose your own file to replace it.
How it works
- Choose an audio file, the format you want, and a quality level (for lossy formats).
- Optionally set a sample rate and channel count (mono or stereo) — leave both on "Keep original" to preserve the source file's settings.
- Click Convert audio — the file is decoded and re-encoded to your chosen format.
- Preview it right on the page, then download the converted file.
How the conversion works
Every audio format pairs a container (how the bytes are wrapped, e.g.
.mp3, .m4a) with a codec (how the sound itself is
encoded, e.g. LAME MP3, AAC, FLAC). This tool loads FFmpeg — compiled to
WebAssembly so it can run inside your browser tab — decodes your file back
to raw audio samples, then re-encodes those samples with the codec your
target format needs:
ffmpeg -i input.wav -acodec libmp3lame -b:a 192k output.mp3
For MP3, OGG, and M4A the -b:a bitrate flag sets how many
kilobits per second of audio detail survives the re-encode — higher
keeps more detail at the cost of a larger file. WAV and FLAC skip that
flag entirely: WAV stores the decoded samples uncompressed, and FLAC
compresses them losslessly, so both keep 100% of the original audio
detail regardless of bitrate.
Sample rate and channels are separate from the codec and apply no
matter which format you're converting to. -ar sets the
output sample rate in Hz (e.g. downsampling to 16 kHz shrinks speech
recordings with little audible loss), and -ac sets the
channel count — 2 for stereo, 1 to fold a stereo file down to mono.
Leaving either on "Keep original" omits that flag, so the source
file's own rate or channel layout passes through unchanged.
FAQ
Does my audio file get uploaded anywhere?
No. The whole conversion runs in your browser using ffmpeg.wasm, a WebAssembly build of FFmpeg — your audio file never leaves your device or touches a server.
Which audio formats can I convert between?
Choose MP3, WAV, OGG, or FLAC as an input, and convert to MP3, WAV, OGG, FLAC, or M4A as the output. The conversion engine bundles its own decoders, so it also accepts less common inputs like AAC, WMA, or Opus.
Why does the first conversion take a moment to start?
The first click loads a ~30MB WebAssembly conversion engine, since it's only fetched when you actually use the tool, not on every page visit. Your browser caches it, so later conversions on this page start instantly.
What's the difference between the lossy and lossless formats?
MP3, OGG, and M4A are lossy — they discard some audio detail to shrink the file, so you can pick a bitrate (128/192/320 kbps) to trade size for quality. WAV and FLAC are lossless and keep the full original audio, so there's no quality setting to choose — FLAC just compresses it losslessly, while WAV stores it uncompressed.
Is there a file size or length limit?
No hard limit is enforced, but everything runs on your device's own CPU and memory, so very large or very long files may be slow or run out of memory on lower-powered devices. It works best for files up to a few hundred MB.
Does this modify or re-encode my original file?
No — your original file is read into memory, converted to the format you chose, and that's it. The source file on your device is never changed.
Can I change the sample rate or convert to mono?
Yes. Set "Sample rate" to resample the audio (e.g. down to 22.05 kHz or 16 kHz for smaller, voice-only files) and "Channels" to force stereo or mono. Leave both on "Keep original" to pass the source file's rate and channel layout through unchanged.
Can I convert multiple files at once?
Not yet — this tool converts one file at a time. If you have several files to convert, run them through one after another; each conversion only takes a few seconds once the engine is loaded.
How we compare
| Feature | Online Tool Store | Convertio | OnlineAudioConverter.com | Sodaphonic |
|---|---|---|---|---|
| No file upload — runs entirely in your browser | ✓ | ✗ | ✗ | ✓ |
| No sign-up or daily conversion limit | ✓ | ✓ | Free tier capped at 5/day | ✓ |
| Preview the result before downloading | ✓ | ✓ | ✓ | ✓ |
| Lossless output options (WAV, FLAC) | ✓ | ✓ | ✓ | ✓ |
| Sample rate control | ✓ | ✓ | ✓ | ✗ |
| Mono/stereo channel control | ✓ | ✓ | ✓ | ✓ |
Convertio and OnlineAudioConverter.com both get the job done, but only after your file is sent to their server. Sodaphonic also converts locally in your browser, but doesn't let you set a target sample rate. Audio Converter now matches the sample-rate and channel controls of the bigger converters, without uploading anything or creating an account.