Convert OPUS to MP3 on Mac (WhatsApp Voice Notes Too)

Pick one of these. All three run on your Mac and upload nothing.

1. ffmpeg (free, Terminal). Install it with Homebrew (brew install ffmpeg), then run the command below.
2. VLC (free, no Terminal). Media > Convert / Save, add the .opus file, choose an MP3 profile, and save. See the VLC site.
3. Smol (paid app). Drop the .opus files on Smol, choose MP3, set a bitrate and convert. Outputs land next to the originals.

ffmpeg -i voice.opus -codec:a libmp3lame -b:a 128k voice.mp3

-b:a 128k sets the MP3 bitrate. For speech, 128 kbps is plenty. For music, raise it. Our audio bitrate guide explains what each step costs and buys.

WhatsApp stores voice notes as Opus audio in an Ogg container, usually with an .opus or .ogg extension. Export the note from the chat, save it to a folder on your Mac, then convert it with any method above.

The result is an ordinary MP3. It plays in QuickTime, Music, Voice Memos imports, GarageBand and every phone. If you have a whole chat of notes, use the loop below instead of converting one by one.

Run this in the folder that holds the files. It writes an MP3 beside each .opus and leaves the originals alone.

for f in *.opus; do
  ffmpeg -i "$f" -codec:a libmp3lame -b:a 128k "${f%.opus}.mp3"
done

Prefer a window to a loop? Smol takes a whole folder, and the batch audio conversion guide covers the options for Finder-based workflows.

Yes, usually. Opus is a newer codec and is very efficient at low bitrates, so an MP3 of the same sound is larger. We encoded a 30 second stereo test tone to Opus at 32 kbps, then converted it to MP3 with ffmpeg on a Mac. The test tone is simpler than real speech, so treat the ratio as a direction, not a promise.

Both MP3s came from the same Opus file. Converting lossy to lossy cannot restore detail Opus already discarded, so a higher MP3 bitrate only makes the file bigger. Match the bitrate to the job. To shrink the result afterward, see how to compress an audio file on Mac.

Not reliably. On the macOS build we tested (27.0.1), the system tools afinfo and afconvert read a 32 kbps Opus file, so Apple’s own plumbing can decode it. Older macOS versions may not, and most apps still refuse the extension. VLC plays .opus on any Mac. Converting to MP3 is the fix when you need to send the file to someone else.

afconvert -f WAVE -d LEI16 voice.opus voice.wav

That gives you a WAV, not an MP3. Apple does not ship an MP3 encoder in afconvert, so use ffmpeg, VLC or an app for MP3. Our best audio converter for Mac roundup compares the options.

For one voice note, use ffmpeg or VLC. Both are free and both do the job in seconds. Do not pay for an app to convert a single file.

Smol earns its $29 (one payment, one Mac) when you convert folders of mixed audio regularly. We dropped an .opus file on it and got an MP3, with nothing uploaded. It also handles OGG and WMA, and it sits in the Finder right-click menu. See pricing.