Made Good Designs

MKV to MP4

Convert MKV to MP4 online for free — when the MKV already contains H.264 or HEVC video and AAC or MP3 audio it's repackaged without re-encoding in seconds; other codecs are converted. Runs privately in your browser: no upload, no watermark.

100% private — your video is processed on your device, never uploaded. Conversion happens on your device; nothing is uploaded.

100% private — runs in your browser

Processing uses your browser’s built-in video encoders (WebCodecs) through the open-source Mediabunny library — your video is never uploaded. Works best in recent Chrome, Edge and Safari; the output is kept in memory, so very large files (several GB) may need a computer with plenty of RAM.

How to convert MKV to MP4

  1. Drop your MKV file in the box.
  2. Click Convert to MP4.
  3. Preview the MP4.
  4. Download it.

What you can use it for

  • Play MKV videos on TVs, phones and consoles that need MP4
  • Import MKV recordings from OBS into editors
  • Share videos on platforms that reject MKV
  • Make videos compatible with PowerPoint and Keynote

More free tools

Editing images?

Convert, compress, resize and vectorize images with our free, private image tools.

See all free image tools →

Related tools

Frequently asked questions

Is MKV to MP4 conversion lossless?

Yes when the codecs are MP4-compatible (H.264/HEVC video, AAC/MP3 audio) — the streams are copied as-is. Other codecs are re-encoded.

What about subtitles and extra audio tracks?

The main video and audio tracks are kept. Embedded subtitles and extra language tracks aren't carried over.

Is my video uploaded?

No. The video is read and encoded by your own browser using its built-in video encoders, so it never leaves your device — even large or private videos stay private.

Is there a file size limit?

There's no upload limit. The finished video is held in memory before download, so files up to a few GB work on most computers; very large files need more RAM.

Which browsers work?

Recent Chrome, Edge and Safari work best (they have hardware video encoders). Firefox 130+ works for most files.