ALL AUDIO TOOLS18
M4A to WAV
Convert M4A to WAV Online — Free & Instant
Decode M4A and AAC audio to uncompressed WAV for editing, mixing or archival.
Nothing is enforced, but the file is decoded to 32-bit float in this tab with the WAV written alongside it at about 10 MB a minute, so a long recording needs many times its own size in memory.
About M4A to WAV
WAV is the format audio software expects. Digital audio workstations, mastering chains, forensic and transcription tools, sample libraries and broadcast delivery specs all assume uncompressed PCM, and several of them will refuse a compressed file outright rather than decode it for you. M4A is the opposite: it is what an iPhone voice memo, a GarageBand bounce, an iTunes purchase or a screen recording's audio track arrives as, and it holds AAC — compressed, lossy, and awkward to edit. Converting bridges the two. The tool decodes the M4A to raw samples and writes them into a standard 16-bit WAV at the file's own sample rate, which is what an editor wants to see. Two things are worth being clear about. The first is size: uncompressed audio runs about 10 MB per minute in stereo, so a 5 MB voice memo can land near 50 MB as a WAV. The second is quality. Decoding to WAV does not restore anything AAC discarded — that information is gone and no conversion brings it back. What the WAV gives you is a lossless container to work in, so that every edit, filter and bounce after this point costs nothing further. Most browsers decode AAC natively; where one will not, an FFmpeg engine served from this site does it instead. Either way the audio is processed in this tab and never uploaded.
Questions
How much bigger will the WAV be?
Roughly ten times, and sometimes more. Uncompressed stereo audio runs about 10 MB per minute at 44.1 kHz, so a 5 MB voice memo becomes something near 50 MB and an hour-long recording lands around 600 MB. That is the format working as intended — WAV stores every sample rather than a compressed approximation.
Does converting to WAV improve the audio?
No. Nothing the AAC encoder discarded comes back, and no conversion can recover it. What the WAV gives you is a lossless container to work in, so that every edit, filter and export after this point costs nothing further. It is a working format, not a repair.
What sample rate and bit depth does the WAV use?
The file's own sample rate — usually 44.1 or 48 kHz — written as 16-bit PCM, which is what audio software expects and what CD-quality means. Channel count is preserved: mono stays mono, stereo stays stereo.
Can I convert iPhone voice memos this way?
Yes. Voice Memos saves M4A, and so do GarageBand bounces and most iOS recording apps. Move the file to your computer via AirDrop, email or the Files app and drop it here. A WAV is what a transcription tool or a DAW will want from it.
Why does Firefox download an engine for this?
Some Firefox builds have no AAC decoder, so the browser cannot open an M4A at all. The tool falls back to an FFmpeg build served from this site — about 31 MB once, then cached — which decodes the file before the WAV is written. That path is heavier on memory too, because it produces a 16-bit WAV of its own on the way.
Is my file uploaded to a server?
No. Transmute processes everything locally in your browser using JavaScript and WebAssembly. Your files never leave your device — there is no server, no upload, no cloud processing.