MKV to MP4 Converter

MKV (Matroska) is a flexible container popular for films and series: one file can hold several audio languages, subtitles and chapters. Phones, TVs, iMovie and many upload forms only take MP4. Most MKV files already contain H.264 or HEVC video, which MP4 can hold too, so this converter copies the video untouched — a full film converts in about a minute — and converts only the parts MP4 players cannot handle. It runs in your browser; nothing is uploaded.

How to use this tool

1. Choose one or more .mkv files.
2. Keep "Copy" for speed and full quality, or re-encode for maximum compatibility (for example 10-bit H.264 anime releases).
3. Choose whether to keep only the first audio track or every language, and whether to keep text subtitles.
4. Press Calculate and download the MP4.

Formula

H.264 / HEVC → copied · AC-3, E-AC-3, DTS, TrueHD, FLAC, Opus, Vorbis → AAC · SRT/ASS → mov_text

AAC and MP3 tracks are copied. Other audio becomes AAC at 192 kbps (384 kbps for 5.1 or 7.1, keeping the channels). Text subtitles become MP4 timed text (styling from ASS is simplified); picture subtitles (PGS from Blu-ray, VobSub from DVD) cannot go into MP4 and are left out. Language labels are kept.

Example

A 45-minute, 1.2 GB MKV episode with H.264 video, an English E-AC-3 5.1 track and English SRT subtitles: the video is copied, the E-AC-3 track becomes AAC 5.1 at 384 kbps and the SRT becomes an MP4 subtitle track. The MP4 is about 1.2 GB and is ready in about a minute or two on a computer.

Large files

The video engine reads your MKV in pieces, but builds the MP4 in memory. On a computer, files up to about 1.5 GB convert reliably (the page asks before starting anything larger); on phones, keep to a few hundred MB. Very large films are better converted with a desktop app such as ffmpeg itself.