How to use it
- Drop your MKV file onto the page.
- Leave H.264 encoding off unless you need maximum compatibility.
- Click Convert to MP4 and download the result.
How MKV to MP4 works
MKV is a flexible container that can hold almost any video and audio codec, plus multiple audio tracks and subtitles. Many devices and editors don't open it, while MP4 plays nearly everywhere. If the MKV contains H.264 or HEVC video and AAC, MP3 or Opus audio, the converter copies those streams into an MP4 without re-encoding: it takes seconds and the quality is identical.
If the video is VP8, VP9 or AV1, tick Encode to H.264 for files that play on iPhones and TVs. Surround AC-3 or E-AC-3 audio that your browser can't convert is copied as is: VLC, TVs and media players handle it, but browsers and some phones may play the video silently. Only the main video and audio track are kept; extra audio tracks and subtitles are dropped.
Everything happens in your browser; nothing is uploaded. Current Chrome and Edge, Safari 16.4+ and desktop Firefox 130+ are supported. For QuickTime files, see MOV to MP4.
Frequently asked questions
Does MKV to MP4 conversion reduce quality?
No, when the streams are copied without re-encoding, which is the default for H.264 and HEVC files.
Are subtitles kept?
No. Only the main video and audio tracks are converted; subtitle tracks and extra audio tracks are left out.
Is my file uploaded?
No. The conversion runs entirely in your browser.
Last updated: November 12, 2026