Step 1: Share your Opus files using the button above or by drag and drop.
Step 2: Click the 'Transform' button to start the transformation.
Step 3: Grab your converted MKV files.
Opus to MKV Transformation FAQ
Is the Opus to MKV converter free?
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Yes. One conversion an hour is free, with no account needed, for a file within the free size limit. A paid plan removes the hourly limit and the size limit, and lets you add several files to one job.
How big an Opus file can I convert to MKV?
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Free conversions have a size limit per file, set by the type of file, and the page tells you when a file is over it. A paid plan removes that limit, so much larger files can be converted.
Can I convert many Opus files to MKV at once?
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Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
Does the Opus to MKV converter work on phones and tablets?
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Yes — the UI is responsive and the conversion pipeline runs server-side, so mobile devices upload-then-download just like desktops. iOS and Android browser file pickers (camera roll, Files app) work end-to-end.
Which browsers does the converter support?
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Chrome, Firefox, Safari (15+), Edge, and Opera. The converter uses standard `<input type="file">` upload — no WebAssembly or PWA dependency — so even older browsers work to upload an Opus and download the MKV.
Are my Opus files kept private?
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Yes. Uploaded Opus files are processed on our own conversion servers, no person reviews them, and they are never shared. The upload and the converted MKV are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy. Opus is the best-sounding lossy codec at low bitrates by a clear margin, and it powers WhatsApp voice notes, Discord and WebRTC.
What if the MKV download does not start automatically?
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Disable any pop-up blocker, then click the download button manually. The result link stays active for 24 hours, so if your network drops mid-download you can retry from the result page without re-uploading the Opus.
How long does Opus to MKV conversion take?
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It depends on the size and length of the file. Small documents and images are usually ready quickly. Long videos take the longest, because most video conversions re-encode every frame. MKV is the archival container of choice because it stores unlimited audio tracks, soft subtitles, chapter markers and cover art in one file. MKV has almost no native hardware support — phones, browsers and TVs usually need VLC or a remux before they will play it.
Do I need to install software to convert Opus to MKV?
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No — the converter runs entirely in your browser plus our servers. No desktop install, no plugin, no browser extension. Just upload, wait briefly, download the MKV.
Can I convert Opus to MKV without creating an account?
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Yes for one-off conversions. Sign up free for batch history, server-side file storage, and higher conversion limits. Premium adds parallel workers, bigger file caps, longer result retention, and no ads.
