Convert .opus files, such as voice messages saved from chat apps, call and meeting recordings or Opus music, into MP3 that opens anywhere. Add a batch, choose the quality and download; the audio never leaves your device.
MP3 quality
Voice messages: chat apps save voice notes as mono Opus at about 16 to 32 kbps. 64 or 128 kbps MP3 in mono is more than enough and keeps the files small.
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How to use the OPUS to MP3
Add your OPUS files: drop them on the box or click Choose OPUS files. Save voice messages from your chat app to your device first.
Pick the MP3 quality: 64 or 128 kbps (Mono) for voice messages, 192 kbps or more for music.
Tick Normalize volume if recordings are quiet.
Press Convert to MP3. Each file shows its progress and new size.
Download each MP3, or press Download all (ZIP).
Recommended MP3 settings for Opus files
Opus source
Typical bitrate
MP3 setting
MP3 size per minute
Voice message / voice note
16 to 32 kbps, mono
64 kbps, mono
0.48 MB
Call or meeting recording
24 to 64 kbps
128 kbps, mono
0.96 MB
Podcast or audiobook
48 to 96 kbps
128 kbps
0.96 MB
Music
96 to 160 kbps, stereo
192 to 320 kbps, stereo
1.44 to 2.4 MB
MP3 size is bitrate ÷ 8 × seconds: 64,000 ÷ 8 = 8,000 bytes per second, so a 2-minute voice note at 64 kbps becomes about 0.96 MB.
Opus versus MP3
Opus is a much newer codec than MP3 and combines two techniques: SILK, designed for speech, and CELT, designed for music. It gives clear speech at bitrates where MP3 sounds muffled, and it has very low delay, which is why calls and chat apps use it. MP3, on the other hand, plays on practically every device, including older car stereos, MP3 players and software that cannot open .opus files.
Keep the Opus file if your devices can play it: it is smaller and sounds as good.
Convert to MP3 to share a recording with someone whose player, editor or website does not accept Opus.
Where .opus files come from
Voice messages saved from chat apps, recordings from browser-based recorders, exported meeting audio and some podcast downloads are often Opus. The audio may be stored in a .opus or .ogg file (Ogg container) or a .webm / .weba file (WebM container); this tool accepts all of them.
Frequently asked questions
How do I convert an OPUS file to MP3?
Add the .opus file to this page, choose a bitrate (128 kbps works well for voice) and press Convert to MP3. The audio is decoded and re-encoded in your browser, then you can download the MP3. There is no upload or sign-up.
What is an OPUS file?
Opus is an open, royalty-free audio codec standardised by the IETF in 2012 (RFC 6716). It works from 6 to 510 kbps and is used for voice messages, video calls, WebRTC, Discord and streaming. .opus files store Opus audio in an Ogg container.
How do I convert a voice message to MP3?
Save or export the voice message from your chat app to your phone or computer (it is usually an .opus or .ogg file), then add it here and convert it at 64 or 128 kbps in mono. The MP3 can be played or shared anywhere.
Why is my MP3 bigger than the OPUS file?
Opus is far more efficient than MP3: a 24 kbps Opus voice note sounds about as good as a much higher bitrate MP3. Use 64 kbps mono for voice to keep the MP3 small; higher bitrates only add size.
Why is the sample rate 48 kHz?
Opus always decodes at 48 kHz, whatever rate the original recording used, so the MP3 is 48 kHz with Keep original. Choose 44.1 kHz if a device or program expects CD-rate audio.
Why will my OPUS file not convert?
The file may be incomplete, for example a voice message that was still downloading. Older Safari versions cannot decode Ogg Opus; Chrome, Edge and Firefox decode it reliably.
Are my voice messages uploaded?
No. Everything happens in your browser, so private messages and recordings never leave your device.