Convert AVI to MKV
Ethical Tube's free AVI to MKV converter turns AVI videos into MKV, a flexible container for video with several audio and subtitle tracks. It runs entirely in your browser, so your videos are never uploaded, and it's free with no sign-up or watermark. The first conversion downloads the FFmpeg engine (10 MB) once, and it's cached after that.
Files are converted on your device and never uploaded.
- Price
- Free
- Uploads
- None, it runs on your device
- Sign-up
- Not needed
- Batch
- Unlimited files
- Output
- MKV, original codecs kept
- First use
- 10 MB download, once
How it works
How to convert AVI to MKV
Add your AVI files
Drop AVI files onto the converter, click to choose them, or paste from the clipboard. Add as many as you like.
Check the settings
MKV is already selected. Keep the original resolution or pick a smaller one, and choose a quality.
Download your MKV videos
Each file gets its own download button as soon as it's ready. Download all saves everything in one ZIP file.
The formats
AVI and MKV at a glance
What is an AVI file?
AVI is a video format Microsoft introduced in 1992. It can hold many codecs, often DivX, Xvid, or MJPEG, and files are usually larger than a modern MP4 of the same quality. Old cameras, webcams, and Windows software still produce it, but phones, Macs, and websites often can't play it. It opens in VLC, Windows Media Player, mpv, and most video editors. QuickTime, iPhone, and many websites can't play most AVI files.
What is an MKV file?
MKV (Matroska) is an open container that can hold almost any video and audio codec, plus several audio tracks and subtitles in one file. It's popular for films, TV recordings, and OBS recordings. Many phones, TVs, editors, and QuickTime can't play MKV, so it's often converted to MP4. It opens in VLC, mpv, Plex, Kodi, Windows Media Player on Windows 10 and 11, and many smart TVs. QuickTime, iMovie, and iPhone can't open it.
Good to know
What changes when you convert AVI to MKV
- MKV can hold almost any codec, so the video and audio are usually copied without re-encoding. That's lossless and takes seconds.
- Only the main video and audio tracks are kept. Subtitles, chapters, and extra audio tracks aren't carried over.
- AVI files are converted with FFmpeg running in your browser. It's slower than a desktop app, so a long HD video can take several minutes.
- The first conversion downloads FFmpeg compiled to WebAssembly (10 MB). It's cached, so later visits start quickly.
- Copy-protected (DRM) files can't be converted.
- Very long videos can run out of memory, especially on phones.
FAQ
Questions, answered
Is this AVI to MKV converter free?
Yes. It's completely free, with no sign-up, no watermark, and no limit on how many files you convert. It costs Ethical Tube nothing to run, because the conversion happens on your own device rather than on a server.
Are my files uploaded anywhere?
No. The conversion runs inside your browser with FFmpeg compiled to WebAssembly, so your files never leave your device. Once the page and the engine have loaded, it even works offline.
Does converting AVI to MKV lose quality?
Not if the codecs already fit: then the video and audio are copied as they are, with no loss. When they have to be re-encoded, the default quality keeps the result visually close to the original. Pick a higher quality for footage you plan to edit.
How long does it take?
When the video can be copied without re-encoding, a few seconds. Otherwise it depends on the video's length and resolution and on your device. With a hardware encoder, a 10-minute 1080p video usually takes a few minutes on a laptop.
Can I convert several AVI files at once?
Yes. Add as many as you like. They're converted one after another, and you can download each MKV file as soon as it's ready or all of them in one ZIP file.
Does it work on iPhone, Android, Mac, and Windows?
Yes, in any current browser on a computer or phone. FFmpeg runs on your processor without hardware acceleration, so long videos are much faster on a computer.
What can open an MKV file?
VLC, mpv, Plex, Kodi, Windows Media Player on Windows 10 and 11, and many smart TVs. QuickTime, iMovie, and iPhone can't open it.
Is there a file size limit?
There's no upload limit because nothing is uploaded. The practical limit is your device's memory: everyday files are fine, and a computer can usually handle videos up to about 2 GB.
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