Convert MKV to MP4 in your browser, with H.264 video copied frame for frame
Processed in your browser. Nothing is uploaded. Updated on 24 Oct 2026.Most MKV files already hold H.264 video and AAC sound, the same streams an MP4 uses, so converting one should not mean re-encoding it. This page moves the frames from the MKV box into an MP4 box unchanged, which takes seconds and keeps every pixel. Vorbis or Opus sound is converted to AAC; VP9 video is re-encoded to H.264. Subtitles and extra audio tracks are left out.
Press Choose a video and pick the MKV file.
Read the note: H.264 video is moved across unchanged, VP9 is re-encoded to H.264, and Vorbis or Opus sound is converted to AAC.
Subtitles and extra audio tracks are left out of the MP4, so keep the MKV if you need them.
Press Convert to MP4 (copy) when the picture is copied, or Convert to MP4 when it has to be encoded.
The MOV to MP4 Converter turns a MOV, MKV or WebM video into an MP4, changing as little as it can.
Copied, not re-encoded. A MOV from an iPhone or a camera, and most MKV files, already hold H.264 or H.265 pictures and AAC sound, which is exactly what an MP4 holds. Only the container differs. So every compressed frame is copied from the old file into the new one as it is: nothing is decoded, nothing is compressed again, and a 1 GB file takes seconds rather than minutes. The page shows how many frames were copied, normally 100 per cent.
Re-encoded, and why. WebM files from screen recorders and browsers usually hold VP9 or VP8 pictures, and some newer files hold AV1. MP4 can technically carry these, but QuickTime, iPhones, many TVs and most editors will not play them from an MP4, so they are decoded and encoded to H.264. That takes roughly as long as the video plays, often less on a computer with a hardware encoder, and softens the picture slightly. Opus, Vorbis, MP3 and FLAC sound is converted to AAC at 256 kbps. Five-channel and six-channel sound is mixed down to stereo.
The rest of the article, and all 6 questions about MOV to MP4 Converter, are on the MOV to MP4 Converter page.
Drop the MOV here and press Convert. iPhone and camera MOV files hold H.264 or H.265 video and AAC sound, which MP4 holds too, so every frame is copied into the new file unchanged. Nothing is compressed again, and the MP4 looks exactly like the MOV.
Yes, when the MKV holds H.264 or H.265 video, as most do. The frames are moved into an MP4 as they are, in seconds. AAC sound is copied; Opus or Vorbis sound is converted to AAC. Subtitles, chapters and extra audio tracks are left out.
WebM files usually hold VP9 or VP8 video, which QuickTime, iPhones and many TVs will not play from an MP4. The page decodes every frame and encodes it as H.264, the format every MP4 player reads. The page says this before you press the button, with the reason.
Sound in Dolby AC-3 or DTS cannot be decoded in a browser, and uncompressed PCM sound inside a MOV is not read here yet, so none of these can go into the MP4. The page warns before converting. A desktop program such as HandBrake converts those files with the sound.
Still stuck? Ask about MOV to MP4 Converter and anybody who knows can answer. No account needed.
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