Convert MKV to MP4 Online Free
Runs 100% in your browser — your files never leave your device.
MKV files confuse phones and consoles; MP4 plays everywhere. This tool converts your Matroska videos into friendly H.264 MP4s privately in your browser when size allows, with server processing as backup — you can delete files sent to our servers right after processing, or let them auto-delete within an hour.
How it works
- 1
Add your file
Drop your file in or click to browse. Small files never leave your device.
- 2
Convert
Large files automatically finish on our servers instead — delete them right after processing, or let them auto-delete within an hour.
- 3
Download
Save the result instantly — original quality preserved as much as the format allows.
About this tool
Converting MKV to MP4
MKV is the collector's container: flexible, metadata-rich, and the home of media libraries served by Plex and Jellyfin. MP4 is the universal video container — H.264 video and AAC audio in a package every device, browser, and platform plays. Converting re-wraps (and where needed re-encodes) the video into the target container: MP4 ends the "works on my Plex, not on my phone" split by re-wrapping into the universal container.. The conversion runs in your browser for typical files, with larger ones finishing on our servers and auto-deleting within an hour.
What to check after converting
Play the result end to end — container conversions occasionally shift timing or drop a compatibility feature the source container allowed. Check that audio plays in sync and the video renders at full quality, and keep the original file untouched as your master.
Frequently asked questions
Does converting between containers reduce quality?
Re-wrapping a video without re-encoding is lossless; where the target codec requires re-encoding, a small quality step applies. The tool handles both cases transparently.
Is my video uploaded anywhere?
Small videos convert entirely in your browser. Larger ones process on our servers and auto-delete within one hour — nothing is kept.
Why would I choose MP4 over MKV?
MP4 ends the "works on my Plex, not on my phone" split by re-wrapping into the universal container.