video / file
MP4 to MKV Converter
Move MP4 video into MKV when you need a more flexible container without changing the content.
This converter is designed as a container change first. When streams are already compatible, it keeps them and rewrites the file as MKV instead of re-encoding.
Upload MP4
Supported input: mp4. Max file size: 100 MB.
Downloads stay available for 1 day on your current access level.
Ready files get a temporary download link that you can open or share.
Audio and video conversions use credits because they need more processing time.
Checking your account and credit balance.
Convert multiple files
If you repeat the same format change often, you can prepare a batch and process several files together.
Batch conversion is available on the Pro plan. Sign in to upload up to 25 files at once for this converter.
Step by step
How to use this converter
- 1
Choose a MP4 file
Start with a supported MP4 source and check that the file is the version you want to convert.
- 2
Review the format notes
MP4 to MKV Converter explains what is preserved, what can change, and which settings matter before upload.
- 3
Upload MP4
Upload the source file, run the conversion, and download the finished MKV result from the temporary link.
- 4
Keep the original
Save your original MP4 file until you have checked that the MKV output fits the next app or publishing flow.
Expected output
You receive a MKV file that matches the stated converter limits. A practical remux-first route for workflows that want MKV container compatibility.
Before you convert
Common issues to check
- - damaged or unsupported source streams can still fail during remux
- - this first slice caps MP4 to MKV jobs at 20 minutes per file
- - this first slice does not expose subtitle or per-track controls
- - some container-specific metadata
- - stream ordering can change
Not ideal for
- - damaged or unsupported source streams can still fail during remux
- - this first slice caps MP4 to MKV jobs at 20 minutes per file
- - this first slice does not expose subtitle or per-track controls
- - some container-specific metadata
- - stream ordering can change
Before you start
You should know the result and the limits before the upload begins.
What stays
- - video and audio streams when remux succeeds
- - duration
- - container-level playback intent
What may change
- - some container-specific metadata
- - stream ordering can change
Known limitations
- - damaged or unsupported source streams can still fail during remux
- - this first slice caps MP4 to MKV jobs at 20 minutes per file
- - this first slice does not expose subtitle or per-track controls
Typical use cases
- - media player compatibility
- - archive workflows
- - container normalization
Available options
- - copy streams without re-encoding
FAQ
What happens during MP4 to MKV conversion?
The converter tries to keep the existing media streams and rewrite them into an MKV container instead of re-encoding the content.
Are uploaded files kept permanently?
No. Files are kept only for a short time and downloads are served through temporary links.
Can quality or formatting change?
Yes. Each converter page calls out what is preserved, what may be lost, and which settings matter before upload.