Audio Converter Pro
Change the format of one or many audio files, or pull the sound out of a video file, and trim, fade or level it on the way. The conversion is done by ffmpeg running inside your browser tab. Free preview · Pro required to export. Listen to up to 15 seconds of one converted file free. Pro exports the full duration and batches.
Free preview · Pro required to export. Listen to up to 15 seconds of one converted file free. Pro exports the full duration and batches.
Why use this tool?
- A device, editor or upload form accepts MP3 but you have a FLAC, an M4A or an Ogg file, and you only need the format changed.
- You want just the soundtrack of a recording: a video file dropped in has its audio extracted and the picture discarded.
- A podcast, voice note or music clip needs a trim, a fade at each end, or a consistent loudness before it is published.
- Large WAV files are slow to send; an MP3 or Opus copy at a sensible bitrate is a fraction of the size.
How to use Audio Converter
- Drop audio or video files onto the drop zone, or click it to browse. You can add several; each shows its size and duration.
- Under "Convert to", choose a Format. Lossy formats show a Bitrate menu (320k down to 64k); WAV and FLAC are lossless and do not.
- Optionally set Sample rate and Channels (mono or stereo), a Start at and End at time for trimming, the Fade in and out slider, and "Normalise loudness to -16 LUFS".
- Press the Convert button, which names the format, for example "Convert 3 files to MP3". The first run downloads the audio engine, so it starts slowly.
- Watch the progress bar, then use Download beside each file, or "Download all as a zip" once more than one has finished.
Features
- Output to MP3, AAC (.m4a), Opus, Ogg Vorbis, WAV or FLAC
- Bitrate choice from 64k to 320k for the lossy formats
- Sample rate options from 16 kHz to 48 kHz, or keep the original
- Mono or stereo output
- Trim by start and end time, entered as seconds, mm:ss or hh:mm:ss
- Fade in and out of 0 to 10 seconds, with the fade-out placed against the trimmed length
- Loudness normalisation to -16 LUFS, a target for how loud the recording sounds rather than its highest peak
- Batch conversion with a before-and-after size total, and a zip download
Supported formats
Accepts MP3, WAV, FLAC, M4A, AAC, Ogg, Opus, WMA and AIFF audio, plus MP4, MOV, MKV and WebM video, from which only the audio is taken. Outputs MP3, M4A (AAC), Opus, Ogg, WAV or FLAC; the output is named after the original file with the new extension.
Tips
- Converting one lossy format to another (MP3 to Opus, say) re-encodes already compressed audio and loses a little more each time. Go back to the original file when you have it.
- Converting an MP3 to FLAC or WAV does not restore lost quality; it only produces a bigger file of the same audio.
- For speech, 22.05 kHz or 16 kHz with mono output makes much smaller files, and a bitrate of 96k or less is usually enough. Music wants 192k or above.
- If a trim time is rejected, check the format: it must be a number of seconds, mm:ss or hh:mm:ss, and the end must be later than the start.
Frequently asked questions
Are my audio files uploaded?
No. The files are read and converted inside your browser by ffmpeg compiled to WebAssembly. The encoder itself, about 32 MB, is downloaded once from a public CDN and then cached by the browser; your audio is not part of that request.
Why is the first conversion slow to start?
The tool has to fetch the ffmpeg engine the first time you convert something. A message says so while it happens. After that the browser keeps it and later conversions begin straight away.
Can I take the audio out of a video?
Yes. Drop an MP4, MOV, MKV or WebM file in, choose an audio format and convert. The video stream is dropped and only the sound is written to the new file.
What is the difference between loudness and peak normalisation?
Peak normalisation scales a file so its single loudest moment reaches a ceiling. Loudness normalisation, which this tool uses, aims for a perceived loudness of -16 LUFS, so a quiet recording with one loud spike is lifted much more than a peak method would allow.
Is there a limit on how many files I can convert?
The tool does not set a file count or size limit. The practical limit is your device's memory, since everything is processed in the browser, so very long files or very large batches can fail on a low-memory device.
Why did one file fail while others worked?
Each file is converted on its own, and a file that ffmpeg cannot read is marked failed with the reason shown next to it, while the rest carry on. It may be damaged or use a codec the engine does not include.
Does it keep tags like title and artist?
It asks ffmpeg to copy the source metadata across. Whether every tag survives depends on what the new format can store.
Can I try this Pro tool without an account?
Yes. Listen to up to 15 seconds of one converted file free. Pro exports the full duration and batches. Your own input is processed locally in your browser.
Will upgrading keep my work?
Checkout and login open in a separate tab. Keep the workspace open to retain inputs, settings and previews. Files stay in that tab only; keep the originals in case you close or reload it. Export access is checked with the server after payment.
Your files are processed directly in your browser and are not uploaded to HubToolify's servers.