Audio Converter

Convert audio between formats entirely inside your browser. Drop a file in, choose the output, and save the result - the recording never leaves your device.

Runs entirely in your browser. Nothing is uploaded.

Pick a conversion

Constant bitrate.

Mono halves the size of speech.

Matching the source avoids a resample.

Drop audio files here, or

Converted on this device. Nothing is uploaded.

MP3 encoding by LAME, via lamejs, used under the LGPL and loaded as a separate file you can replace.

How to use the Audio Converter

  1. Choose the output format

    MP3 when something has to play it, WAV when something has to edit it.

  2. Add your audio

    Drop in a file and it is decoded by the codecs already in your browser. Nothing is transmitted.

  3. Check the bitrate and sample rate

    The sample rate is read from your file, so the default already matches it. Raise the bitrate if the source is a good one.

  4. Download the result

    Play it back on the page first, then save it. The before and after sizes are shown so you can see what the change cost.

Which format should you convert to?

MP3 is the format that plays on anything. Car head units, gym equipment, old MP3 players, cheap Bluetooth speakers, church PA systems, voicemail systems - all of them take MP3 and a good number of them take nothing else. It is lossy, so it discards detail to get small, and at 192 kbps or above most people cannot hear what went.

WAV is uncompressed PCM: the raw samples, with a 44-byte header in front of them. It is roughly ten times the size of an MP3 and it is what audio editors, samplers and older recording software want to be given. Converting to WAV does not improve anything - it stores exactly what it was handed, artefacts included - but it removes the container and the codec from the equation, which is sometimes the whole point.

M4A is AAC audio in an MP4 container. It is what an iPhone Voice Memo, a QuickTime recording and most of an iTunes library are. It is a better codec than MP3 at the same bitrate, and it is supported by markedly less hardware, which is why most people converting M4A are converting it away.

Converting never recovers quality

Every lossy encode throws detail away permanently. Converting an MP3 to WAV gives you a file ten times the size containing exactly the same audio, artefacts and all - "WAV" is not a synonym for "CD quality", it is a synonym for "not compressed further". Converting an M4A to MP3 puts a second lossy encode on top of a first, which is strictly worse than either alone.

The question worth asking before any conversion here is not "which is better" but "what is going to open this file". That is the only reason any of these conversions is the right thing to do, and each of the pages below leads with the honest answer for its own pair.

Why this one does not upload your audio

Audio is unusually personal. A voice memo is a recording of someone talking, an interview is a recording of two people, and a rehearsal take is unreleased work. Every hosted converter takes the upload before it does anything, which means the recording sat on infrastructure belonging to a company you have not met, under a retention policy you did not read.

This decodes with the audio codecs already built into your browser and encodes in a background worker on your own machine. There is no upload, no queue, no per-file size cap set by a server - only what your own device can hold in memory, which is why files over 200 MB are turned away rather than crashing the tab.

Frequently asked questions

Is my audio uploaded anywhere?
No. Decoding uses the codecs already built into your browser and encoding runs in a worker on your own device. Nothing is transmitted, which is what makes this usable for interviews, voice memos and unreleased recordings.
Which formats can I convert between?
MP3 and WAV as output. Input is anything your browser can decode, which covers M4A, MP3, WAV, and usually FLAC and OGG as well.
Why is there a 200 MB limit?
Because the conversion happens in your browser. Decoding expands compressed audio to raw floating-point samples - roughly 10 MB per minute per channel - and a large enough file exhausts the tab rather than converting slowly. The limit is your device, not an upload cap.
Does converting to WAV improve the sound?
No. WAV stores exactly what it is given. Converting a 128 kbps MP3 to WAV produces a file about ten times larger containing the same audio, with the same compression artefacts, and no detail recovered.
Why is the conversion slower than an upload-based converter?
Because it is running on your machine rather than on a server farm, in one background thread. The page stays responsive while it works, and the file never goes anywhere. For a typical song it is a few seconds.