Convert AVI to MKV
To convert AVI to MKV, add your .avi file below and press the button: it's processed on your own device and you download the result, with nothing uploaded. It's free, needs no account, and works with files up to 500MB.
About converting AVI to MKV
AVI (.avi) files can be converted to MKV entirely in your browser — no software to install, no file upload, and no account required. The conversion runs on a WebAssembly build of ffmpeg directly on your device.
Technical comparison
| AVI | MKV | |
|---|---|---|
| Category | video | video |
| Compression type | Varies (codec-dependent; often uncompressed or lightly compressed) | Varies (codec-dependent — a container, not a codec) |
| Typical file size | Large — often stores uncompressed or lightly-compressed video | Varies — depends entirely on the codecs it wraps |
| Transparency support | No | Depends on the wrapped codec |
How to convert AVI to MKV privately
Every step below runs on a WebAssembly build of ffmpeg inside this browser tab. Your .avi file is never uploaded to a server — there's no network request carrying it anywhere.
Add your AVI file
Drag and drop, or click to select, a file (.avi). It's read straight from disk into browser memory — no upload step exists.
Convert locally
FreePrivateConvert converts it to MKV using a WebAssembly build of ffmpeg, entirely within this browser tab.
Download the result
Save your converted .mkv file. It only ever existed in this tab's memory — closing the tab without downloading discards it completely.
Convert AVI to MKV with ffmpeg (command line)
Prefer the terminal? This is the exact ffmpeg command this page runs for you:
ffmpeg -i input.avi -c:v libx264 -preset veryfast -crf 23 -c:a aac output.mkv- -i input.avi
- Your AVI file.
- -c:v libx264
- Encode the video as H.264, the format virtually every phone, browser and TV plays.
- -preset veryfast
- Encoding speed vs. file size trade-off: veryfast encodes quickly with a slightly larger file.
- -crf 23
- Constant quality level (lower = better quality and bigger file; 18-28 is the usual range, 23 is the default).
- -c:a aac
- Encode the audio as AAC.
- output.mkv
- The MKV file to create. ffmpeg picks the container from this extension.
Don't have ffmpeg installed? You don't need it: use the converter at the top of this page. It runs the same conversion on your own device, and your file is never uploaded.
FAQ
- Is my file uploaded anywhere?
- No. Your file is read and processed inside this browser tab and never leaves your device. You can confirm it in your browser's developer tools: the Network tab shows no upload.
- Does converting AVI to MKV reduce quality?
- The video is re-encoded as H.264 at CRF 23 (ffmpeg's default quality level, "veryfast" preset) with AAC audio. That looks very close to the source for most footage, but it is a lossy re-encode, so fine detail and grain can soften slightly.
- Is there a file size limit?
- Yes: 500MB per file. There's no account and no limit on how many files you convert.
- What's the difference between AVI and MKV?
- AVI (Audio Video Interleave) and MKV (Matroska Video) store data differently. AVI: varies (codec-dependent; often uncompressed or lightly compressed). MKV: varies (codec-dependent — a container, not a codec). MKV is an open-standard container that can hold effectively unlimited video, audio, and subtitle tracks — popular for rips and archives with multiple language/subtitle options.
- Why convert AVI to MKV?
- Common uses for MKV: Archiving video with multiple audio/subtitle tracks; Media server libraries (Plex, Jellyfin); High-quality video rips and remuxes. No practical limit on the number of embedded audio, subtitle, or chapter tracks, unlike MP4's more constrained structure.
- What MIME type does a .mkv file use?
- video/x-matroska, the standard type for Matroska Video.
- What is the ffmpeg command to convert AVI to MKV?
- Run: ffmpeg -i input.avi -c:v libx264 -preset veryfast -crf 23 -c:a aac output.mkv. This is the exact command FreePrivateConvert runs for this conversion, so you can use this page instead of installing ffmpeg: it runs the same conversion inside your browser.
Learn more: What is an MKV file
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