Convert MKV to MP4
100% private — runs on your device, never uploaded. Works offline once loaded.
MKV is an open container that will hold almost anything, which is exactly why software refuses it: phones, smart TVs, editing suites and social uploaders mostly want MP4. The video inside an MKV is very often ordinary H.264 with AAC sound, and when it is, this rewraps it into MP4 without decoding a single frame — seconds rather than minutes, and no loss of quality. Where an MKV holds something MP4 cannot carry, such as VP9 video or multiple subtitle tracks, the picture is re-encoded to H.264 instead and the extra tracks are dropped, which is the trade any MKV to MP4 conversion has to make.
Frequently asked questions
Will I lose subtitles or extra audio tracks?
MP4 keeps one video and one audio track here, so additional tracks and embedded subtitles are dropped. Extract subtitles separately if you need them.
Why are some MKV files instant and others slow?
If the video inside is already H.264 or HEVC it is copied straight across. VP9 and other codecs MP4 cannot carry have to be re-encoded, which takes real time.
Is there a file size limit?
No. The file is processed on your own machine, so the limit is your device rather than an upload cap.
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