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ConvertAnyVideo

MP4 to MKV Converter

Convert MP4 videos to MKV in seconds. Change resolution, quality and frame rate if you like — all in your browser.

or drop files here

Up to 1 GB per file · Files never leave your device

  • 100% free
  • No sign-up
  • No upload — private
  • No watermark

How to convert MP4 to MKV

  1. Add your MP4 files

    Click “Choose Files” or drag and drop your MP4 videos onto this page.

  2. MKV is selected

    The output is already set to MKV. Open Advanced settings if you want to change the quality, resolution or length.

  3. Convert and download

    Click Convert. Your MKV file is ready in moments — nothing is uploaded.

About the formats

MP4

MPEG-4 Part 14

MP4 is the most widely supported video format today. It usually stores H.264 or H.265 video with AAC audio and plays on almost every phone, browser, TV and editing app.

MKV

Matroska Video

MKV (Matroska) is a flexible open container that can hold several audio tracks, subtitles and chapters in one file. It is popular for movies and series.

Frequently asked questions

How do I convert MP4 to MKV?

Click “Choose Files” and select your MP4 file (or drag it onto the page). MKV is already selected as the output, so just click Convert and download your MKV file when it’s ready.

Will I lose quality converting MP4 to MKV?

When the video inside your MP4 file is compatible with MKV, it is copied without re-encoding, so there is no quality loss at all. Otherwise it is re-encoded at high quality. You can pick the quality yourself in Advanced settings.

Is it safe to convert MP4 files here?

Yes. Conversion runs inside your own web browser, so your files are never uploaded to our servers or anyone else’s. Nobody can see them, and nothing is stored after you close the tab.

Is the MP4 to MKV converter free?

Yes, it’s completely free. There’s no sign-up, no watermark and no limit on how many files you convert. Each file can be up to 1 GB.

Can I convert several MP4 files at once?

Yes. Add as many MP4 files as you like and convert them in one go, then download them one by one or together as a ZIP file.

Convert MP4 to other formats

Convert other formats to MKV