Convert MP4 to MKV, Free
Upload your MP4 file and get a MKV in seconds. No account, no watermark.
How to convert MP4 to MKV
MKV (Matroska Video) is an open-standard container format that supports multiple video, audio, and subtitle tracks in a single file with no codec restrictions. Converting MP4 to MKV is useful when you need to add external subtitle files to a video, combine multiple audio language tracks, or archive video in a container that imposes no format restrictions on its contents.
BoltConverter re-wraps your MP4 into an MKV container on our servers. When the video codec is H.264, re-encoding is typically not required and the conversion is fast with no quality loss. After conversion, both files are deleted from the server immediately.
Upload your MP4 file
Click the upload area or drag your .mp4 file onto the page.
Video is re-wrapped into MKV
BoltConverter moves the video and audio streams from the MP4 container into an MKV container on our servers, without re-encoding.
Download the MKV file
Click Download to save the MKV to your device. It will play in VLC, Plex, Kodi, and any MKV-compatible media player.
Frequently asked questions
Why would I convert MP4 to MKV?
MKV supports a wider range of codecs and multiple audio/subtitle tracks. It is popular for media archiving and home theater setups using Plex or Kodi, where multiple audio languages and subtitle tracks are common.
Will there be quality loss?
No. BoltConverter re-wraps the streams without re-encoding when possible, so the video and audio quality remain identical to the original MP4.
Can I add subtitle tracks when converting to MKV?
This converter re-wraps the existing streams. Adding external subtitle tracks to the MKV requires a tool like MKVToolNix after the conversion.
Will the MKV play everywhere the MP4 would?
MKV is less universally supported than MP4. Smart TVs, older mobile devices, and some platforms may not play MKV natively. VLC, Plex, and Kodi support MKV on virtually all platforms.
Are my files stored on the server?
No. Both the uploaded MP4 and the resulting MKV are deleted from our servers immediately after you download the result.