Drop an MKV above, choose a quality and download an H.264 MP4 that plays on iPhones, Android, TVs, editors and websites. Encoding runs on your device with ffmpeg.
Why convert MKV to MP4?
MKV (Matroska) is a flexible container popular for recordings and downloads, but many phones, TVs, video editors and upload sites do not accept it. MP4 is accepted almost everywhere.
How it works
1. Drop the MKV.
2. MP4 is selected; pick High, Good (default), Medium or Low quality.
3. Convert & Download — ffmpeg re-encodes in your browser and shows progress.
MKV vs MP4
MKV: open container that can hold almost any codec plus several audio tracks, subtitles and chapters.
MP4: more limited, but universally supported. Here it carries one H.264 video track and one AAC audio track.
Quality notes
Only the main video and audio tracks are converted; extra audio languages, subtitles and chapters are not carried over. At High quality the result is visually identical to the source.
Common use cases
Playing OBS or screen recordings on a phone; importing recordings into editors that reject MKV; uploading to sites that require MP4.
Frequently asked questions
Are subtitles kept?＋
No. Only one video and one audio track are converted. Extract subtitles separately if you need them.
Which audio track is used?＋
One track, chosen automatically by ffmpeg (normally the main track). Files with several languages keep only that one.
Will quality drop?＋
Re-encoding adds a little loss; the High setting keeps it visually identical.
Why is OBS recording in MKV?＋
OBS recommends MKV because a crash does not corrupt the file. Converting to MP4 afterwards is the usual workflow.