Audio
Convert MP3 to WAV on Mac (and What It Can’t Restore)
To convert MP3 to WAV on a Mac, run afconvert in.mp3 out.wav -d LEI16 -f WAVE in Terminal. It is built in, free, and writes a standard 16-bit WAV. The Music app does the same through File > Convert.
The WAV will be about 11 times bigger and will sound the same as the MP3. It will not sound better. MP3 throws audio away when it is encoded, and no converter can put it back.
How do I convert MP3 to WAV in Terminal?
afconvert in.mp3 out.wav -d LEI16 -f WAVELEI16 is 16-bit little-endian PCM, the format editors, samplers and video tools expect. Sample rate and channels carry over from the MP3. To convert every MP3 in a folder:
for f in *.mp3; do afconvert "$f" "${f%.mp3}.wav" -d LEI16 -f WAVE; doneThe originals stay where they are. If you already use ffmpeg, ffmpeg -i in.mp3 out.wav gives the same kind of file.
Can the Music app convert MP3 to WAV?
Yes. Open Music > Settings > Files > Import Settings, set Import Using to WAV Encoder, and click OK. Select the MP3 in your library and choose File > Convert > Create WAV Version. A WAV copy appears beside the MP3.
It adds duplicates to your library and leaves the import setting changed. For editing jobs that are not about your music collection, Terminal is tidier.
How big is the WAV, and does it sound better?
We encoded a 30-second stereo fixture (44.1 kHz, 5,292,078 bytes as WAV) to MP3 at three settings, converted each MP3 to WAV with afconvert, and compared the energy above 17.5 kHz, where MP3 encoders usually cut.
| Source | MP3 size (bytes) | WAV from it (bytes) | Energy above 17.5 kHz |
|---|---|---|---|
| Original WAV | - | 5,292,078 | -66.3 dB |
| MP3, 128 kbps | 481,070 | 5,296,096 | -74.4 dB |
| MP3, LAME V0 | 573,783 | 5,296,096 | -65.8 dB |
| MP3, 320 kbps | 1,202,676 | 5,296,096 | -67.4 dB |
Two things stand out. Every WAV is the same size whatever the MP3 started as, because WAV stores every sample. And the 128 kbps file lost about 8 dB of high-frequency content that the WAV does not recover. A bigger file is not a better file. For more on bitrates, read audio bitrate explained.
Why convert MP3 to WAV at all?
There are real reasons. Some editors, hardware samplers, broadcast systems and game engines only accept PCM. Editing a WAV avoids stacking a second MP3 encode on top of the first. Decoding once also saves CPU on slow devices.
The rule: convert to WAV, edit, and export from the WAV. Do not convert MP3 to WAV and then back to MP3 expecting the same file. That second encode loses more. Going the other way is covered in convert WAV to MP3 on Mac.
Which sample rate and channels should the WAV use?
Keep whatever the MP3 has. A 44.1 kHz stereo MP3 should become a 44.1 kHz stereo WAV, and afconvert does that by default. Resampling adds a processing step and gains nothing. If your video editor works at 48 kHz, add -r 48000 and let the converter handle it once, rather than letting the editor resample on every export.
Length is safe too. Our 30.000-second MP3 produced a 30.000-second WAV, so a track will not drift out of sync with a video. Mono MP3s such as spoken-word files stay mono and give a WAV half the size of a stereo one. Run afinfo file.mp3 first if you want to see the rate, channels and bitrate before converting.
When is Smol the wrong tool for this?
For one or two files, afconvert or the Music app is enough. Skip Smol.
Smol is worth $29 (once, one Mac) when you convert often: drop a folder of mixed MP3, M4A and FLAC files, pick WAV, and watch per-file progress, or right-click files in Finder. Nothing is uploaded, and outputs are copies beside the originals by default. See the buy page or our audio converter comparison. If you need many files at once, batch audio conversion covers the workflow.
How we checked this
Encoded a synthetic 30-second stereo fixture to MP3 at three settings, converted each to WAV with afconvert on macOS 27.0.1, then measured sizes with stat and high-frequency energy with ffmpeg astats. Facts last checked . We make Smol, so treat our claims about it with the same care as any vendor’s, and see our editorial policy.
MP3 to WAV: common questions
Does converting MP3 to WAV improve quality?
No. The WAV holds exactly what the MP3 decodes to, including everything the MP3 encoder discarded. It sounds the same, only as a much larger uncompressed file. In our test, a 128 kbps MP3 lost about 8 dB of content above 17.5 kHz, and the WAV made from it did not get it back.
Why is the WAV so much bigger than the MP3?
WAV stores every sample with no compression. Stereo 44.1 kHz 16-bit audio is about 176 KB per second. In our test, a 128 kbps MP3 of 481,070 bytes became a 5,296,096-byte WAV, roughly 11 times larger, and a 320 kbps MP3 became the same WAV size.
Is there a free way to convert MP3 to WAV on a Mac?
Yes, two. The afconvert command in Terminal and the Music app with its import encoder set to WAV are both built in and run offline. QuickTime Player and Preview cannot do this. Free online converters work but upload your file, which matters for private recordings.
Should I use 16-bit or 24-bit for an MP3 to WAV conversion?
Use 16-bit. MP3 does not carry 24-bit detail, so a 24-bit WAV is about 50% bigger and holds the same audio. Only choose 24-bit when your editing session is set to it and refuses mixed formats. The afconvert flag for 16-bit is LEI16.
Can I turn a WAV back into the original MP3 quality?
No. Re-encoding the WAV to MP3 creates a new lossy file with a second round of loss. Keep the original MP3 as your master, and use the WAV only as a working copy. If you want smaller files after editing, compress from the edited WAV once.
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