You get an MP3 file that car stereos, phones, editors and default players open without extra software.
To convert Opus to MP3, add the .opus file, keep MP3 as the output and download the result. Opus is usually a chat voice note, and plenty of players cannot open it, while MP3 plays almost anywhere. Both formats are lossy, so the audio is compressed a second time. In our test a 10-second stereo file came out 19% smaller, a mono voice-style file came out 70% larger, and the title, artist and album tags were not kept.
Transfers use HTTPS, and files converted on the free tier are deleted after 24 hours, so the result is not a long-term archive. Quality depends on the source file, so open the MP3 file once before you share it.
Opus (Opus Interactive Audio Codec)
A lossy audio codec standardised by the IETF in RFC 6716 (2012) that scales from 6 kbit/s speech to 510 kbit/s stereo music. Files are usually Opus streams in an Ogg container and carry the .opus extension, which is how chat apps such as WhatsApp save voice notes. Many older players, car stereos and Apple apps cannot open it without a converter.
MP3 (MPEG-1 Audio Layer III)
The oldest widely used lossy audio format. Its compression is less efficient than newer codecs, but virtually every car stereo, portable player, operating system and audio program can open an MP3.
A 10-second stereo Opus test file (96 kbps, tags set) and a 6-second mono one, both made by us
Renaming voice.opus to voice.mp3 does not work, because the audio inside is still an Opus stream. The converter decodes it and encodes it again with the LAME MP3 encoder, so the new file is an MP3 inside as well as by name.
In our test a 48 kHz stereo Opus file became a 48 kHz stereo MP3, and a 48 kHz mono file stayed mono. Nothing was resampled or mixed down.
With no bitrate option set, our stereo file was written at 128 kbps constant and our mono file at 64 kbps constant. We did not see a bitrate setting on this page during the test.
We converted a stereo sweep tone and a mono voice-style tone with ffprobe readings before and after, so every number on this page comes from a file we uploaded ourselves.
Drop the .opus file on the box or choose it from your device. Keep the original, because it is the copy that has been compressed only once.
Check that MP3 is the output format and start the conversion. The page may label an .opus file as OGG, which is how it showed ours, and the result is still an MP3. In our test a 10-second file took 3.8 seconds from the click to Completed.
Save the MP3 and play it on the device you care about. If you need the title or artist, add the tags again in a tag editor, since they are not carried over.
Add an Opus file and get an MP3 back, with nothing to install. The page states what the conversion does to size, tags and high frequencies, using numbers from files we converted ourselves.
The upload box shows the live size limit before you add a file. Signing in raises it; a paid plan does not change it.
OPUS in, MP3 out. Pick another output on the converter if you need a different format.
Files are encrypted in transit over HTTPS and processed on indox infrastructure.
Free-tier files are kept for 24 hours after the job finishes, then deleted automatically.
| What you see | Why | What to do |
|---|---|---|
| The MP3 is bigger than the Opus file | A low-bitrate Opus file, such as a voice note, was written at a higher MP3 bitrate | Keep the Opus file if size matters, or accept the larger MP3 for the compatibility |
| The title and artist are missing | The tags are not carried over by the converter | Add them again in a tag editor |
| The page calls the file OGG | Opus audio is stored in an Ogg container, so the page may show OGG to MP3 | Carry on. The output is still an MP3 |
| The file has an .ogg extension | Some apps save Opus voice messages as .ogg | Use OGG to MP3 for that extension |
| The conversion fails | The recording may be damaged or exported incompletely | Re-export or re-download the recording and try again |
| Compared on | Opus | MP3 |
|---|---|---|
| Standard | IETF RFC 6716, published in 2012 | A de facto file format, widely adopted for delivering audio to end users |
| Bitrate range | 6 to 510 kbit/s | Usually fixed choices such as 128 kbps; our test files used 128 and 64 kbps |
| Typical use | Chat voice notes and streaming, usually in an Ogg file | Music libraries, car stereos, portable players and editors |
| Where it plays | Newer players; many older players, car stereos and Apple apps cannot open it | Virtually every player, operating system and audio program |
| Tags | Stored in the Ogg file | ID3 metadata before or after the audio |
| Converting between them | Cannot be copied into an MP3 file | Needs a decode and a new encode from Opus |
Facts checked on November 5, 2026
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Add the .opus file to the converter in your browser, keep MP3 as the output and download the result. Nothing is installed on your computer. In our test a 10-second file took 3.8 seconds from the click to Completed, though your file may take longer.
A little, yes. Opus and MP3 are both lossy, so the sound is decoded and compressed again. On our sweep test tone the content above 16 kHz fell by 5 dB. For a spoken voice note the difference is usually small, but it is not zero, so keep the Opus file as your master copy.
Some Apple apps and many older players cannot open Opus. Converting to MP3 gives you a file they can play. On a computer, a player such as VLC opens Opus directly, so you may not need to convert at all.
For the same file size, Opus is the more modern codec and is standardised in RFC 6716. MP3 is older but opens almost everywhere. Choose Opus when the player supports it and MP3 when compatibility matters.
It depends on the Opus bitrate. Our 159 kbps stereo file became a 128 kbps MP3 and shrank by 19%. Our 38 kbps mono voice-style file became a 64 kbps MP3 and grew by 70%. Low-bitrate voice notes usually grow, and high-bitrate music files shrink.
Yes. WhatsApp saves voice notes as .opus. A Telegram voice message saved with an .ogg extension may hold the same Opus audio, and the OGG to MP3 page handles that extension. Use whichever page matches the extension on your file.
No. In our test the Opus file had title, artist and album tags and the MP3 had none of them. Only an encoder tag remained. Add the tags again in a tag editor if you need them.
No. The extension is only a label, and the audio inside is still Opus. Many players refuse it or play nothing. The audio has to be decoded and encoded again as MP3.
We did not see a bitrate setting on this page during our test, so we cannot promise one. With nothing set, our stereo file was written at 128 kbps and our mono file at 64 kbps.
If ffmpeg is installed on your computer, a command such as ffmpeg -i voice.opus -c:a libmp3lame -b:a 192k voice.mp3 does the same kind of re-encode and lets you pick the bitrate. This page is the shorter route when you have one or two files and do not want to set up software.