MKV to MP4 Converter
Convert MKV files to MP4 instantly and privately. File Converts runs entirely in your browser, so your MKV is never uploaded to any server.
Works offline after you have used it once: the engine downloads the first time and is kept. About 30 MB, once.
MKV is the most capable container in common use: multiple audio tracks, multiple subtitle tracks, chapters, and almost any codec. That capability is exactly why so little plays it. Phones, browsers, smart TVs and editing software largely expect MP4, and MKV remains a media-player format.
Because MKV usually holds H.264 or HEVC already, converting to MP4 is normally a remux: the video is copied into the new container without re-encoding, so it is fast and lossless. What does not survive is what MP4 cannot represent as cleanly — extra audio tracks beyond the first, and subtitle formats MP4 does not support. If the file carries a dub or subtitles you rely on, check the result before deleting the source.
Everything runs in your browser through a WebAssembly build of FFmpeg, so a large file is never uploaded — which for video is the difference between seconds and an hour.
How to convert MKV → MP4
Drop your MKV file into the converter above — it stays on your device.
Choose MP4 as the output. File Converts picks the smartest settings automatically.
Click Convert and download your MP4 file instantly.