How to convert MP4 to Matroska (MKV)
- 1
Upload your file
Drag and drop a file or click to select one. Keep this page open while the file uploads and converts.
- 2
Convert MP4 to Matroska (MKV)
NexMedia converts MP4 to Matroska (MKV) on its own servers. Processing time depends on the file size and how busy the queue is.
- 3
Download the converted file
When the conversion finishes, the download appears on this page. Your converted file is kept for 2 hours, then deleted.
About MP4
MP4 (MPEG-4 Part 14) is a container format standardised by ISO. It usually holds H.264 or H.265 video with AAC audio, and it can also carry subtitles and chapter markers.
It is the most widely supported video format: phones, browsers, smart TVs and video sites all play it.
The video inside an MP4 is almost always compressed with a lossy codec, so every re-encode loses a little quality.
Convert MP4 to MKV online free, no account required — MKV is a flexible open container for video with any number of audio and subtitle tracks.
Change MP4 to MKV without losing quality — convert MP4 to MKV free in your browser.
Why is my MP4 file so large? MP4 video is already compressed with H.264 or H.265, so a lower bitrate or resolution shrinks the file at the cost of some quality.
About Matroska (MKV)
Matroska (MKV) is an open container format that can hold almost any video and audio codec, any number of audio and subtitle tracks, chapters and attachments.
It is popular for films and series with several audio languages and subtitle tracks, and for archiving video.
Many phones, browsers and TVs do not play MKV files directly, even when they support the codecs inside.
Why convert video to MKV? When one file must carry several audio languages, subtitle tracks and chapters, no container holds them as flexibly.
What changes when you convert MP4 to MKV
- The MP4 is re-encoded into MKV at the default quality settings, so the result looks close to the original but is not bit-identical.
Settings you can change
Before you convert MP4 to MKV, you can adjust: Video codec, Rate control, Quality (CRF), Video bitrate, Resolution, Width, Height, Scale fit, Frame rate, Encoder preset, Audio codec, Audio bitrate, Trim start, Trim duration, and Remove metadata.
Limits
Each plan sets a maximum file size and a number of conversions per day, and video and audio files also have a maximum length. Guests can convert files up to 100 megabytes and 5 per day; a free account raises this to 500 megabytes and 25 per day; paid plans go up to 100 gigabytes.
Your converted MKV file is kept for 2 hours, then deleted.
MP4 to MKV: questions and answers
Does converting MP4 to MKV reduce quality?
The MP4 is re-encoded into MKV at the default quality settings, so the result looks close to the original but is not bit-identical.
What is the difference between MP4 and MKV?
MP4 is a widely supported video container, usually holding H.264 video and AAC audio. MKV is a flexible open container for video with any number of audio and subtitle tracks.
Can I change the settings when converting MP4 to MKV?
Before you convert MP4 to MKV, you can adjust: Video codec, Rate control, Quality (CRF), Video bitrate, Resolution, Width, Height, Scale fit, Frame rate, Encoder preset, Audio codec, Audio bitrate, Trim start, Trim duration, and Remove metadata.
Do I need an account to convert MP4 to MKV?
No. You can convert MP4 to MKV without an account; signing in raises the file-size and daily limits.
How long is my converted MKV file kept?
The MKV file you convert from MP4 is kept for 2 hours, then deleted automatically.
When I convert MP4 to MKV, is the video re-encoded?
The MP4 is re-encoded into MKV at the default quality settings, so the result looks close to the original but is not bit-identical.
Will converting MP4 to MKV change my original file?
No. The conversion reads your MP4 and writes a new MKV file, leaving your original MP4 file untouched.