Opus to MP3 converter
Convert Opus to MP3 in your browser, with nothing uploaded.
Processed in your browser. This file is converted on your device and is never uploaded.
Converter
.opus up to 250 MB. You can also drag a file here.
No file selected.
About this tool
This page converts Opus to MP3 in your browser. The file is read from your own device, decoded and re-encoded by code running on it, and handed back as a download. It is never uploaded, because there is no conversion server here to upload it to.
Opus is the newest of these, standardised in 2012, and it is what voice and video calls run on. It was designed to sound good at bitrates where older formats fall apart.
Opus is what a voice message or a call recording arrives as, and it is superb at that job and understood almost nowhere outside the app that produced it. Converting is how a recording stops being trapped in one piece of software.
Nothing else plays in as many places. An MP3 works on hardware old enough to predate streaming and on anything sold since, which is why it remains the answer whenever the question is whether the file will open at all.
Audio conversion needs a real codec, so the first conversion in a session downloads FFmpeg compiled to WebAssembly — a few megabytes, fetched once and then reused. It is the same file for every visitor and it arrives before you have chosen anything, so it says nothing about your recording. Everything after that happens on your device.
Supported formats and limits
- Input
- .opus
- Output
- .mp3 (audio/mpeg)
- Output name
- The original name with the new extension, for example track.opus becomes track.mp3.
- File size limit
- 250 MB
- Processing
- In your browser. The file is not uploaded.
Opus against MP3
| Feature | Opus | MP3 |
|---|---|---|
| Compression | Lossy — detail is discarded permanently | Lossy — detail is discarded permanently |
| Three minutes, stereo | About 2 MB | About 3–7 MB |
| Artist and album tags | Yes | Yes |
| Plays in browsers | Yes | Yes |
| Introduced | 2012 | 1993 |
| Quality setting | You choose it | You choose it |
When you would want this
Playing it on something that will not read the original
Car stereos, gym equipment, older iPods, and cheap MP3 players each read a short list of formats and reject everything else without explaining why. Converting to a format on that list is usually the whole fix, and it is why MP3 is asked for far more often than it is chosen on merit.
Publishing speech
Podcast hosts and submission forms almost always want MP3, often with a size limit attached. Speech survives heavy compression far better than music does, so the lowest quality setting is frequently the right one here.
How to use it
- Choose a Opus file, or drag one onto the box.
- Pick a quality. Higher sounds better and produces a larger file; the middle setting is what most people want.
- Select convert and wait. The first run also loads the audio engine, so it takes longer than the ones after it.
- Download the result. Nothing is kept: leaving or resetting the page releases it.
Limitations
- Both Opus and MP3 are lossy, so this conversion compresses an already-compressed recording. The result is slightly worse than the input no matter which quality you pick, and converting back and forth repeatedly makes it audibly worse.
- The output is usually larger than the input — roughly 3 to 7 megabytes for three minutes of stereo. That is expected and is not a sign anything went wrong.
- Opus is lossy, and its encoder's decisions are final.
- Support outside browsers and messaging apps is thin; many players and most car stereos will not open one.
- The audio engine is a few megabytes and is downloaded the first time you convert something in a session. On a slow connection that wait is real, and it happens before the conversion starts rather than during it.
- One file at a time. Audio conversion is heavy enough that running several at once is a good way to exhaust a phone's memory.
- A long recording takes a long time. Converting an hour of audio runs for minutes rather than seconds, and the tab has to stay open while it does.
Common problems
The result is larger than the file I started with.
The output format stores more per second than the input did. That is what it is for, and it is not an error.
If size matters more than fidelity, use a lossy format such as MP3 or OGG instead, or lower the quality setting.
The result sounds duller or thinner than the original.
A lossy encoder was run over audio a lossy encoder had already been run over, and each pass removes something.
Convert from the least-processed copy you have rather than from an export of an export, and choose the highest quality setting.
The Opus file will not open in anything except a browser.
Opus is young and its support is concentrated in browsers and messaging apps. Most desktop players, editors, and hardware never gained it.
Convert it once, into the format the tool you actually want to use reads. Editors in particular are far more likely to accept a WAV or an MP3.
It is taking far longer than expected.
The first conversion of a session downloads the audio engine, and long recordings take proportionally long to process.
Leave the tab open and in the foreground. A background tab is throttled by the browser and will crawl.
Other ways to do this
Keeping it and using a browser to play it
Every current browser plays Opus. If the only problem is that one desktop program cannot open it, dragging the file into a browser tab is a way to listen without converting anything or losing anything.
A desktop audio application
Audacity, foobar2000, and similar programs convert audio and do a great deal else besides. They are the better choice for batches of hundreds of files or for work that needs editing as well as conversion. They are a download and an installation, which is the trade.
FFmpeg on your own machine
This page runs FFmpeg compiled to WebAssembly. The native command-line version does the same conversion faster, handles thousands of files in a loop, and exposes every option there is. If you already have it installed, use it.
Not converting at all
Check first whether the thing you are trying to play actually refuses the format. Modern phones, browsers, and media software read far more than they did a decade ago, and a conversion you do not need costs quality for nothing.
Frequently asked questions
- Does converting to MP3 lose quality?
- It depends on the format you are converting to, and this page says which case it is in the limitations above. A lossless output stores what it is given exactly; a lossy one discards detail to be smaller. Neither can recover anything the source had already lost.
- Which quality setting should I choose?
- The middle one, unless you have a reason. It is indistinguishable from the original for most listeners on most equipment. Choose the highest if the file is going into a library you intend to keep, and the lowest for speech, which survives compression far better than music.
- Are the artist and album kept?
- Where the output format has somewhere to put them, yes. WAV does not, so those pages say so plainly. Cover art is more fragile than text tags and is the first thing to be dropped.
- Is there a limit on how long the recording can be?
- The limit is on file size rather than duration, and it is stated above. In practice a long recording is limited by patience and by memory: everything happens on your device, so an hour-long file will take minutes and will use real memory while it does.
- Can I convert back the other way?
- The file will convert back, but quality does not return with it. Anything a lossy encoder discarded is not in the file to be recovered, so a round trip leaves you with something worse than where you started rather than back where you began.
- Will the file get bigger?
- Yes, usually a great deal bigger. Opus stores three minutes in two to four megabytes where MP3 needs three to seven, so a conversion that keeps the quality roughly intact will roughly double the size. That is the price of a format everything reads.
- Is the result the same as what a desktop program would produce?
- Yes. This is FFmpeg, the same software most desktop converters use underneath, compiled to run in the browser. The encoders are identical, so the output is too. What differs is speed, because a browser sandbox is slower than native code.
- Do I need to install anything or create an account to use Opus to MP3 converter?
- No, to all of it. Opus to MP3 converter runs inside the browser you already have, with no sign-up, no download, no watermark on the result, and no cap on how many files you convert. There is nothing to uninstall afterwards either, because nothing was installed.
- Does Opus to MP3 converter work offline?
- After the first conversion, yes. Audio work needs the FFmpeg engine, which is a separate download of a few tens of megabytes fetched the first time you convert something. Once your browser has cached it the work is entirely local and a connection is no longer needed.
- How large a file can Opus to MP3 converter handle?
- The limit is 250 MB. It is a deliberate one rather than a technical ceiling: the real constraint is memory, and a file that decodes to more than the device can hold fails in a way that is hard to explain. Phones run out well before laptops do, which is why the limit is set where it is.
- Can I convert several files at once with Opus to MP3 converter?
- Not here: this tool takes one file at a time, because what it does depends on choices you make about that particular file. Convert them one after another, or look at the batch converters in the same category, which are built for a folder at a time.