Video conversion
Convert MP4 to MKV
Updated Jul 2026
MP4 is the video format that plays almost anywhere, on phones, browsers, and streaming apps. MKV is a container built to hold high-quality video along with multiple audio tracks and subtitles. Converting MP4 to MKV just repackages the file, and doing it on your own computer means the video never has to leave your machine.
- Extension
- .mp4
- Type
- Video
- Typically
- The universal video format
- Compression
- Lossy
- Extension
- .mkv
- Type
- Video
- Typically
- High-quality video containers
Convert MP4 to MKV on your own computer. Nothing uploads.
How to convert MP4 to MKV
- Open Morphjet and drag in the MP4 files you want to convert. Add a single video or a whole folder at once.
- Choose MKV as the output format.
- Convert. Because MKV can hold the same video and audio without re-encoding, the picture and sound come through unchanged, and nothing leaves your machine.
MP4 vs MKV: what actually changes
| MP4 | MKV | |
|---|---|---|
| Opens everywhere | Yes, plays on phones, browsers, game consoles, and smart TVs | No, many phones and browsers can't open MKV without a separate player |
| Quality | Lossy, compressed when the video was recorded or exported | Unchanged, MKV holds the same video and audio without re-encoding |
| File size | Compact | About the same as the MP4, since nothing is re-compressed |
| Multiple audio tracks and subtitles | Limited support | Built for this, can hold several audio tracks, subtitle tracks, and chapters in one file |
| Typical use | Sharing, streaming, and everyday playback | Archiving masters, home media libraries, and multi-language releases |
When to convert, and when not to
Convert MP4 to MKV when you're archiving a video with multiple audio tracks or subtitles, building a home media library, or want a container that doesn't force a quality-losing re-encode.
Keep the MP4 if you need to play the file on a phone, share it on social media, or open it in a browser, since MKV isn't reliably supported in those places.
Why not just use an online converter?
Video files often carry more than picture and sound; embedded metadata can include the device used, timestamps, and sometimes location. Uploading an MP4 to an online converter to get an MKV sends that file to a stranger's server, even if only for a few seconds. Converting on your own computer keeps the video, and whatever is embedded in it, entirely on your machine.
Questions
Does converting MP4 to MKV lose quality?
No, in most cases. Converting to MKV just repackages the same video and audio streams into a different container without re-encoding, so the picture and sound come through exactly as they were.
Will an MKV file play on my phone or in my browser?
Not always. MP4 is supported almost everywhere, but many phones, browsers, and streaming apps don't open MKV without a separate player installed. Keep an MP4 copy if you need broad playback.
Why would I want MKV instead of MP4?
MKV is built to hold more than one video, audio, or subtitle track in a single file, which makes it useful for archiving a movie with multiple languages, commentary tracks, or subtitle sets.
Does the MKV keep the video's metadata?
Yes. Chapters, subtitle tracks, and most metadata carry over from the MP4 into the MKV during conversion.
Can I convert MP4 to MKV without uploading the file anywhere?
Yes. A desktop app like Morphjet converts the file on your own computer, so it never travels over the internet. You can even do it with your wifi off.
Morphjet converts MP4, MKV, and 1,800+ other formats, all on your machine. Launching this July.