Convert M4A to WAV
Convert an M4A into an uncompressed WAV that any audio editor will import. M4A is what an iPhone voice memo is saved as and what iTunes ripped to for years, so this is usually a recording of somebody talking on its way into transcription software or an editing session. The file grows about tenfold and sounds the same — the reason to do it is that the software at the other end insists.
Use this without the search next time. Prathom Workbench puts Prathom's tools in your toolbar.
Add to Chrome — freeDrop your M4A file here, or click to browse
Up to 50 MB. Deleted automatically after 30 minutes.
What it does
- Uncompressed 16-bit PCM output
- For editors and transcription tools that require WAV
- Reads iPhone voice memos and iTunes files
- No watermark and no sign-up
How to use M4A to WAV
- 1
Add the M4A
Drop the file in or choose it from your computer, up to 50 MB, no account needed.
- 2
Convert
The AAC audio inside is decoded to 16-bit PCM samples and written as a WAV with no further compression.
- 3
Import it
The WAV opens in every audio editor and in tools that reject compressed formats.
Where these files come from
M4A arrives from two places, and both are Apple. Voice Memos on an iPhone saves recordings as M4A, and iTunes ripped CDs to it for years once Apple moved away from MP3.
The first is by far the more common reason anyone converts one. A phone in a pocket or on a table is now the default recording device for interviews, lectures, meetings and consultations, and what comes off it is an M4A that then has to go into something else — transcription software, an editor, an analysis tool.
That destination is what decides the format. It is not an audio quality decision at any point.
How it works
The AAC track inside the M4A container is decoded to 16-bit PCM samples, and those samples are written into a WAV. Nothing encodes on the way out — WAV stores samples as they are, which is precisely why so much software accepts it and nothing else.
The file grows by roughly a factor of ten. That is not waste; it is the size audio occupies when no encoder is deciding what to leave out.
Voice Memos is a recorder people did not choose
Almost nobody sets out to record in M4A. They open Voice Memos because it is on the home screen, or they hit record in a meeting app, and the format is whatever that software writes.
That has a consequence worth knowing: the settings were chosen for you too. Voice Memos records at a modest bitrate suited to speech and to storing hundreds of recordings on a phone, not at anything a studio would pick. So the ceiling on what you can do with the file was set before you knew you would need it — which is an argument for extracting early and working from the WAV, not for expecting the WAV to be better than the recording.
The same is true of iTunes rips. Whatever bitrate was the default in the year the CD went in is what the library has.
Keep the M4A
The original is a tenth the size and sounds identical, so there is no reason to discard it and every reason to keep it. Make the WAV when a tool needs one, use it, and delete it when the session is finished. Treat it as a working file rather than a copy of the recording.
An hour of interview is a large WAV
Worth planning for if you are converting a long recording. Uncompressed stereo at CD quality is about ten megabytes a minute, so an hour becomes roughly six hundred megabytes, and a day of interviews becomes several gigabytes.
Mono halves it, and a great deal of spoken-word recording is effectively mono anyway — a phone lying on a table between two people is not capturing a stereo image worth preserving. If your transcription tool accepts mono, converting to mono WAV rather than stereo is the single easiest saving available, and it costs nothing that matters for speech.
Examples
An iPhone voice memo for transcription
Voice Memos saves M4A. Several transcription and speech-analysis tools accept WAV only, particularly the ones used in research and legal work.
An iTunes track for an older editor
Audio software from before AAC was universal often imports WAV and AIFF and refuses everything else.
Frequently asked questions
Will the recording sound better as a WAV?
No. M4A holds AAC, which is lossy — the encoder permanently discarded what it judged inaudible, and that information is not stored anywhere to be recovered. Decoding to WAV reproduces exactly what the M4A contains at full precision, which is what it already sounded like. The file becomes larger, not better.
Why do transcription tools want WAV?
Because uncompressed audio is simpler and more predictable to process. A decoder is one less dependency, one less thing to get wrong, and one less place where a codec's own artifacts could interfere with speech analysis. It is a practical engineering preference rather than a claim that WAV sounds better, and it is common in research, medical and legal transcription.
Is M4A the same as AAC?
Effectively. M4A is an MP4 container holding an AAC audio track, which is what Apple software produces. A bare `.aac` file is the same audio without the container. The distinction matters for what software will open the file and not for what it sounds like.
How big will the WAV be?
About ten times the M4A. Uncompressed stereo at CD quality runs to roughly ten megabytes a minute whatever it contains, because every sample is stored at full size regardless of whether the passage is complex or silent. An hour-long interview becomes a file of several hundred megabytes.