Convert MP4 to MKV
Usually nothing is re-encoded: the tracks go into MKV as they are, in seconds and with no loss.
They open in the converter with MKV selected.
Browse filesFiles stay on your device. Going the other way? MKV to MP4
What changes
MP4 files normally carry H.264 video and AAC audio, which MKV accepts as they are, so the converter copies the tracks untouched: in seconds and with no loss. If not, or if you change the quality, size, scale or trim, the video is decoded and compressed again, and loses a little more detail.
If it’s copied, it’s about the same size as the MP4: only the container changes. If it’s re-encoded, the size stays about the same.
When it’s worth it
Choose MKV for: Video collections with several audio tracks and subtitles. Holds any codec, plus chapters and real subtitle tracks.
Stay with MP4 for: Phones, websites, social networks, and TV.
How to convert MP4 to MKV
- Drop the MP4 files on this page, or browse for them. Up to 200 at once.
- The converter opens with the files loaded and MKV selected.
- Press Convert, then save each file or all of them as a ZIP.
Questions
Does converting MP4 to MKV lose quality?
Usually not. With the default settings the tracks are copied without re-encoding. Quality only drops if you change the quality, size or trim, or if the file uses a codec MKV doesn’t accept.
What is the MKV format?
Matroska, an open container that can hold any codec in separate tracks, with subtitles as real tracks instead of burned-in text. That flexibility is why it’s the favorite for archiving and for fansubs.
What is the MP4 format?
A container that holds a video track, one or more audio tracks and metadata, and nothing else: which codec sits inside is a separate question. H.264 or H.265 video with AAC audio is the combination almost everyone means by MP4.
Are the files uploaded?
No. The file is opened in this tab, converted here and saved from here. There’s no account and no watermark.
How many files can be converted at once?
Up to 200 per batch and about 2 GB per file, within the memory this device has available.