How to use the MP4 to MKV converter
- Choose your MP4 video or drop it on the box.
- Check the settings. "Same as original" resolution is fastest and lets fast mode copy compatible videos without re-encoding. Lower it to 720p for a smaller file.
- Click "Convert to MKV". A progress meter shows how far along it is.
- Download your MKV.
Why convert MP4 to MKV?
MKV can hold extra audio languages, subtitles and chapters, and is preferred by Plex, Kodi and media servers. MP4 to MKV is a lossless repack.
- MP4: usually lossy, so quality drops a little each time it is re-encoded.
- MKV: holds unlimited audio and subtitle tracks.
- MKV: open and royalty-free.
The video and audio are copied without re-encoding, so quality is identical and the conversion takes seconds.
MP4 vs MKV
| MP4 | MKV | |
|---|---|---|
| Full name | MPEG-4 Part 14 | Matroska Video |
| Type | Video | Video |
| Created by | Moving Picture Experts Group (MPEG) (2001) | the Matroska open-source project (2002) |
| Compression | Lossy | Lossy |
| Typical codecs | H.264 + AAC | H.264, HEVC or VP9 + AAC, AC3, DTS or Opus |
| Best for | Sharing videos online, phone recordings, social media uploads and streaming | Movies with several languages or subtitles, OBS recordings and archiving |
| Plays on | Windows, macOS, iPhone, Android, smart TVs, game consoles and every modern browser | VLC, MPV, Kodi, Plex and most smart TVs; iPhone, iPad, QuickTime and many video editors do not open MKV |
Does converting MP4 to MKV lose quality?
Often none. When the MP4 contains H.264 video, MKV can hold it as it is, so fast mode copies the streams without re-encoding. Other codecs (including HEVC while "Play everywhere" is ticked) are re-encoded at "Balanced" quality, which looks the same as the original to most people.
How long does it take?
Seconds when fast mode applies, even for a full film. If the video must be re-encoded, expect a few minutes for a long HD video.
What is an MP4 file?
MP4 is a container that usually holds H.264 or H.265 video with AAC sound. It is built on Apple's QuickTime file structure and became an ISO standard in 2001. Because almost every phone, browser, TV and editing app can play it, MP4 is the safest choice when you need a video to just work.
What is an MKV file?
MKV (Matroska) is a free, open container that can hold almost any video, audio and subtitle format in one file, including many audio languages and subtitle tracks. That flexibility makes it popular for movie and series files and for screen recorders like OBS.
Frequently asked questions
How much does the MP4 to MKV converter cost?
Nothing. It is free with no registration, no watermark and no limit on how many files you convert.
Do you keep a copy of my files?
We never receive them. All processing happens on your device, so there is nothing for us to store or delete.
Will the MKV sound and look as good as the MP4?
Often none. When the MP4 contains H.264 video, MKV can hold it as it is, so fast mode copies the streams without re-encoding.
Can I convert MKV back to MP4?
Yes, use the MKV to MP4 converter.
An MP4 plays without sound. What should I do?
The audio may use a codec your player does not support (for example AC3). Convert it to MP4 again so the sound becomes AAC.
Does it work on iPhone and Android?
Yes, in Safari, Chrome and other modern mobile browsers. Short files work best on phones; for long or high-resolution videos a computer is faster.