M4A to WAV Converter

Get the PCM out of an M4A as a WAV file, without uploading it. The use for this is software that will not read an MP4 container - not an improvement in the audio, which stays exactly as it was.

Runs entirely in your browser. Nothing is uploaded.

FromM4AAAC in an MP4 container
ToWAVUncompressed PCM

WAV is uncompressed; bitrate does not apply.

Mono halves the size of speech.

Matching the source avoids a resample.

Drop M4A files here, or

Converted on this device. Nothing is uploaded.

How to use the M4A to WAV Converter

  1. Drop in your M4A files

    iPhone voice memos, QuickTime recordings and iTunes AAC all work. Nothing is transmitted.

  2. Choose mono for speech

    A voice memo recorded in stereo is usually two copies of the same thing. Mono halves the file with no loss that matters.

  3. Download the WAV

    About 10 MB per minute for stereo. Expect a large file - that is uncompressed audio.

What you actually get

An M4A is AAC audio inside an MP4 container. This decodes the AAC to raw samples and writes them into a WAV with a plain PCM header. The audio is unchanged: everything AAC discarded when the file was made is still missing, and nothing has been added. What changes is that the result is now a format that opens in software which has never heard of MP4.

That is the whole reason to do this. A sampler, an older audio editor, a transcription pipeline, a game engine, a piece of broadcast kit - all of these routinely take WAV and nothing else. Handing one of them an M4A does not fail gracefully; it usually does not fail at all, it simply refuses to see the file.

Encoder delay, and why the length may shift slightly

AAC encoders add a short run of silence at the start of a file and pad the end to a whole frame. A decoder is supposed to strip both, and browsers do, but the exact handling is not identical everywhere - so a WAV decoded here can differ from one produced by a different tool by a handful of milliseconds.

For listening this is invisible. It matters if you are aligning the audio sample-accurately against video or against other tracks in a session, in which case line it up once after converting rather than assuming the offset carried over.

When an M4A will not decode

The `.m4a` extension covers more than one thing. Apple Lossless sits in the same container with the same extension and no browser decodes it; a `.m4p` is a DRM-protected iTunes Store purchase and decodes nowhere by design. If a file is refused, one of those is the likely explanation.

The other cause is the browser rather than the file. AAC is a licensed codec, so Chromium builds without the proprietary codecs - most Linux distribution packages - cannot read M4A at all. Chrome, Edge and Safari can, as can Firefox on Windows and macOS. The page checks when it loads and warns before you pick a file.

Frequently asked questions

Does converting M4A to WAV improve the audio?
No. The AAC inside the M4A is lossy, and decoding it to PCM stores exactly what is left at about ten times the size. Convert because something needs a WAV, not for the sound.
How large will the WAV be?
About 10 MB per minute for stereo at 44.1 kHz. A one-hour interview is roughly 600 MB, which is why mono is worth choosing for speech.
Is my audio uploaded anywhere?
No. Decoding and writing both happen in your browser. For voice memos and interviews that is the point of using this rather than a hosted converter.
Why was my .m4a refused?
Most likely it is Apple Lossless or a DRM-protected .m4p, which share the container but decode in no browser. The other possibility is a browser built without the AAC decoder.
Will the WAV be exactly the same length as the M4A?
Within a few milliseconds. AAC carries encoder delay and end padding that the decoder strips, and the exact handling varies slightly between tools.