MKV Compressor
Shrink a Matroska file without repacking it into another container.
Drop files, or click to browse
MKV files only — processed one at a time
Frequently asked questions
What's the difference between quality and resolution here?+
Quality controls how aggressively each frame is compressed; resolution controls the pixel dimensions. Lowering either shrinks the file — combine both for the biggest savings.
Will the output still play everywhere?+
Yes — the MKV container and codec choice are kept broadly compatible with players and editors.
Is my video uploaded anywhere?+
No, compression runs locally in your browser using its own built-in media codecs.
Is there a maximum file size?+
There's no fixed upload limit — since everything runs on your device, the practical limit is your browser's available memory, which handles typical clips and even fairly long recordings without issue.
How do I compress a MKV?+
Drop your MKV into the box above, pick a quality tier (and optionally a lower resolution), and download the smaller result once it finishes.
About MKV
What is MKV?
MKV (Matroska) is a flexible open container that can hold multiple audio tracks, subtitles, and chapters alongside the video.
Full MKV format guide →MKV files can balloon quickly, especially with high-resolution source material. Compressing trims the file down to something that uploads faster, loads faster, and takes up less space — without needing to change the format itself.
How it works
- 1
Drop your file in
Drag your video onto the box above, or click it to browse — there's no account to create and no upload to wait on.
- 2
Adjust the slider
Drag the quality slider and watch the estimated file size update in real time.
- 3
Download the result
Your browser processes everything locally and hands you a download link the moment it's done — nothing was ever sent to a server.
Is it private?
Everything happens locally, inside this browser tab. Your video is read from disk, processed with WebAssembly running on your own device, and handed back to you as a download — it's never transmitted anywhere, so there's nothing to intercept and nothing stored on a server.
Common use cases
- Archiving video with multiple language tracks or subtitles
- Uploading a clip to social media
- Sending a video over email or chat
- Freeing up storage on a phone or laptop
Supported formats
This is one of many pairings the video toolkit handles. In total it covers:
Other compressors
Format details
About MKV files+
MKV (Matroska) is a flexible open container that can hold multiple audio tracks, subtitles, and chapters alongside the video.
Matroska was designed from the ground up as an open, extensible container, meaning a single MKV file can bundle several audio tracks (say, multiple languages), several subtitle tracks, and chapter markers, all switchable during playback — something older containers like AVI and even MP4 handle less gracefully. That flexibility made it the format of choice for archiving TV shows and films with multiple language options, though a handful of phones and streaming devices still expect MP4 and need MKV converted first.
How to open a MKV file
Opens readily in VLC Media Player. For real editing, use DaVinci Resolve, Adobe Premiere Pro (with an extension).
Good for
- supports multiple audio/subtitle tracks in one file
- open format, no licensing fees
Watch out for
- not natively supported by some phones and TVs without an app
Need another format? Try the full Video Compressor, or explore all video tools.