How to convert MKV to MP4
- Drop your MKV file in.
- See whether it can be repackaged (fast, full quality) or needs re-encoding.
- Press “Convert to MP4” and save.
MKV and MP4 are just containers
MKV (Matroska) is a flexible container popular with recording software like OBS. It often holds the same H.264 or HEVC video an MP4 can hold. In that case we copy the video into an MP4 container without touching the picture, which takes seconds and keeps the quality exactly.
If the MKV holds VP9 or another codec MP4 players don’t expect, it’s re-encoded to H.264. Sound that isn’t AAC is converted to AAC.
Recorded with OBS?
OBS records to MKV by default because MKV files survive a crash. Converting to MP4 afterwards is the usual next step before uploading or editing, and it’s exactly what this tool does.
Good to know
- Only the main video and sound tracks are kept. Extra audio tracks and subtitle tracks are dropped.
- For maximum compatibility with older devices, tick “Maximum compatibility” to force H.264.
Questions
Will I lose quality converting MKV to MP4?
Not when the video is repackaged: the picture is copied as is. Re-encoding is done at high quality.
What about multiple audio tracks or subtitles?
This version keeps the main video and sound track only.
Is there a watermark?
No. The video you save is exactly what the encoder produced: no watermark, no logo, no sign-up.
Is my video uploaded anywhere?
No. The tool runs inside your browser and uses your device’s own video encoder. Your file is read from your device, processed there and saved back. You can confirm this in your browser’s network panel: nothing is sent while a video is processed.
Which browsers does it work in?
It works best in Chrome and Edge on a computer. It needs a browser feature called WebCodecs. If your browser doesn’t have it, the page tells you before you start.