Convert MP4 to MKV
Repackage MP4 videos as Matroska MKV files. Always takes just seconds — MKV accepts any codec without re-encoding.
Free · No signup · Files never leave your device
Drag and drop a video file
or click to browse
Compatible videos are repackaged in seconds without re-encoding — you'll see whether yours qualifies before converting.
How it works
Drop your MP4 file
It stays on your device — nothing is uploaded.
Converted to MKV locally
Compatible streams are repackaged right in your browser — usually done in seconds with zero quality loss.
Download the result
Preview the MKV and download it — free, no watermark.
Frequently asked questions
Usually seconds. Most MP4 files carry video and audio codecs that MKV also supports, so the streams are repackaged into the new container without re-encoding — no quality loss, no long wait. The tool tells you before converting whether your file qualifies.
Usually not at all: when the codecs are compatible, the conversion just moves the same video and audio data into a new container — bit-for-bit identical quality. Only incompatible streams are re-encoded, and the tool tells you beforehand.
MKV is the most flexible video container: it holds any codec, multiple audio tracks, chapters, and rich subtitles, which makes it popular for archiving and media servers like Plex and Jellyfin.
Yes. The converter is completely free, with no signup, watermarks, or limits. We make money from our video translation service, not from this tool.
No. The conversion happens locally in your browser using WebAssembly. Your file never leaves your device — you can even disconnect from the internet once the page has loaded.