MP4 to MKV Offline Converter
Convert MP4 videos to MKV format completely offline in your browser
Loading Video Processing Engine
This tool uses FFmpeg.wasm for video processing. The first time you use it, it will download the processing engine (~25MB). This only happens once and enables powerful offline video conversion.
Drop your MP4 videos here
or click to select MP4 files
Converted Videos
Why Convert to MKV?
Multiple Streams
MKV supports multiple video, audio, and subtitle streams in one container.
Embedded Subtitles
Keep subtitles and metadata embedded directly in the file.
High Quality
MKV preserves video quality using lossless stream copying.
Frequently Asked Questions
What is MKV format?
MKV (Matroska Video) is a flexible container format that supports multiple video, audio, and subtitle tracks in a single file. It's ideal for archiving and long-term storage.
Will I lose video quality?
No. This converter uses stream copying, which preserves the original video and audio quality without re-encoding.
How long does conversion take?
Since we copy streams without re-encoding, conversion is very fast—typically just a few seconds per file.