Free converter · Lossy re-encode
Convert WAV to M4A
Short answer
Drop your WAV file into the converter below and download the M4A file. It runs in your browser with FFmpeg, for files up to 100 MB; nothing is uploaded. The file is re-encoded to AAC audio in M4A, audio only. Re-encoding takes longer than a container swap and costs some quality; how much depends on the clip and on the quality setting, and at the converter's default setting the loss can be visible, so keep the original.
Maximum file size: 100 MB. The first conversion loads a ~30 MB converter engine, once per visit. Nothing is uploaded - conversion runs on your device.
Uncompressed WAV to AAC inside M4A. · Lossy re-encode · Browser-side via FFmpeg WASM - nothing uploaded.
Key takeaways
- M4A is AAC audio in an MP4 container; the converter encodes the WAV with ffmpeg's native AAC encoder at about 128 kbps.
- Measured: 1,921,102 bytes became 162,700 bytes (-91.5%), AAC at 127.7 kbps.
- AAC is lossy; the FFmpeg AAC guide gives a rule of thumb of 64 kbps per channel for audible transparency, so 128 kbps for stereo.
- M4A at this bitrate is about the same size as MP3 at 128 kbps; choose by what your player supports.
Measured: what you get
Measured on the soundtrack of a 10 second excerpt of Big Buck Bunny (animated film; (c) Blender Foundation, CC BY 3.0), stereo, 48 kHz, using the same ffmpeg arguments this converter passes to its WebAssembly build, run with ffmpeg 6.1.1. Results describe this file.
| Check | Result |
|---|---|
| Input | WAV, 1,921,102 bytes, 48 kHz stereo |
| Output | M4A, 162,700 bytes (-91.5%), AAC 127.7 kbps |
| For comparison: same WAV as MP3 | 160,749 bytes, 128 kbps |
| Time, native ffmpeg | 0.43 s |
| Time, converter's WebAssembly core, 3 s WAV | 0.2 s |
WAV vs M4A
| WAV | M4A | |
|---|---|---|
| Full name | Waveform Audio File Format | MPEG-4 audio |
| What is inside | Uncompressed PCM audio | AAC (or Apple Lossless) audio in an MP4 container |
| Compression | Uncompressed | Lossy or lossless |
| Best for | Editing and mastering, where every sample matters; very large files | Apple devices and voice memos |
What you get
AAC audio in M4A, audio only. Uncompressed WAV to AAC inside M4A.
Why choose M4A over MP3
M4A is an MP4 container, so it can carry metadata and chapters that a plain MP3 stream does not. The FFmpeg AAC guide gives 64 kbps per channel as a rule of thumb for audible transparency: 128 kbps for stereo and 384 kbps for 5.1. We did not compare AAC and MP3 listening quality at equal bitrates; at 128 kbps the two files in our test were almost the same size.
Set the bitrate yourself
ffmpeg -i in.wav -c:a aac -b:a 192k out.m4a- The converter uses the encoder's default of about 128 kbps.
Questions people ask
Is this WAV to M4A converter free and private?
Yes. It is free, needs no account and runs entirely in your browser, so the file never leaves your device.
Will converting WAV to M4A reduce quality?
Some, because M4A is lossy or lossless and the file is re-encoded. How much depends on the clip and on the quality setting, and at the converter's default setting the loss can be visible, so keep the original. For uploads, the platform re-encodes again anyway.
Is there a file size limit?
Files up to 100 MB. The first conversion downloads a converter engine of about 30 MB once per visit; larger files are better handled by a desktop app such as HandBrake or FFmpeg.
Is M4A lossy?
M4A usually holds AAC, which is lossy. It can also hold Apple Lossless.
How big is the M4A?
162,700 bytes for 10 seconds of stereo in our test, about 128 kbps.
Is M4A better than MP3?
We did not compare listening quality; at 128 kbps our two files were almost the same size. Compatibility usually decides: MP3 plays almost everywhere.
Can I keep quality exactly?
No. Any WAV to lossy conversion discards information; keep the WAV as a master.
More converters
Sources and how we checked
- MDN: Media container formats
- MDN: Web audio codec guide
- MDN: Image file type and format guide
- FFmpeg documentation: stream copy
- FFmpeg Documentation: ffmpeg (stream selection, -map, -c copy) (read 2026-10-08)
- FFmpeg Wiki: Encode/AAC (bitrate rule of thumb) (read 2026-10-08)
- Blender Foundation: Big Buck Bunny (CC BY 3.0), the clip used for the measurements (read 2026-10-08)
Reviewed October 8, 2026. What the converter writes was measured with ffprobe on the same FFmpeg build your browser downloads; format descriptions follow MDN's media guides.