MP4 to MKV Converter

Convert MP4 files to MKV online, for free, with nothing to install.

To convert MP4 to MKV, select or drop your .mp4 file above, check that MKV is chosen as the output, and click Convert. This conversion runs on our server, and your files are deleted 72 hours later.

What is an MP4 file?

MP4 – MP4 video. MP4 is the video format that plays everywhere: phones, browsers, TVs and social networks. It usually holds H.264 pictures and AAC sound. Converting makes a new file: the video is decoded and encoded again, so converting from a format that lost detail never brings it back.

MP4 Converter →

What is an MKV file?

MKV – Matroska video. MKV (Matroska) is a flexible open container that can hold any number of video, sound and subtitle tracks. Media players love it; phones and some TVs do not. Converting makes a new file: the video is decoded and encoded again, so converting from a format that lost detail never brings it back.

MKV Converter →

How to convert MP4 to MKV

  1. Click Select File, or drop your .mp4 files anywhere on this page. You can add several at once.
  2. Check that MKV is chosen as the output format. On this page it is picked for you.
  3. Click Convert. When a file has to go to our server, the button says Upload and convert instead.
  4. Click Download next to each file when it's done.

MP4 vs MKV: how they compare

MP4MKV
LayoutMoving pictures and soundMoving pictures and sound
EditableIn video editorsIn video editors
Created byMPEG, 2001Matroska team, 2002
Best forVideo that must play on any deviceFilms with several sound tracks and subtitles

Good to know

  • The video is decoded and written as an MKV file by ffmpeg: H.264 pictures and AAC sound, at a fixed quality. The first picture track and the first sound track are kept; subtitles and other tracks are left out.
  • Pictures wider than 1080p are made 1920 pixels wide. Interlaced video (DVD, TV, camcorders) is deinterlaced.
  • The server converts about as much video as it can in 10 minutes: a long or large video is refused at once with how long it would take, and can be cut shorter first.

Frequently asked questions

Is converting MP4 to MKV free?

Yes. Everyone gets 25 free credits a day, with no account needed. Conversions on our server use one credit per started minute of work, so most cost a single credit. Credits reset at midnight UTC.

Are my MP4 files uploaded anywhere?

This conversion runs on our server, because converting video needs ffmpeg, which does not run in a browser. Your file is sent over an encrypted connection, and both it and the result are deleted 72 hours after the conversion. The server has no internet access while it works on your file.

How large can the MP4 file be?

Up to 1 GB per file. This conversion runs on our server, which accepts files up to that size.

Will the MKV look the same as the MP4?

The picture and sound are decoded and encoded again at a fixed quality, so the MKV looks and sounds very close to the MP4 but is not bit for bit the same. Sizes up to 1080p are kept; the first picture track and the first sound track are kept.

Can I convert several MP4 files at once?

Yes. Add as many files as you like; they are converted one after another, and each one gets its own Download button.

How long does converting MP4 to MKV take?

In our tests a one-minute 1080p video at 8 Mbit/s took about 26 seconds to become an MKV file. Time grows with length and picture size and shrinks for smaller pictures; a video that would need more than about 8 minutes is refused at once, with the time it would take.

Convert MP4 to other formats

Convert other videos to MKV

All video formats

Updated