MP4 to MKV
Repackage MP4 into flexible MKV format - perfect for adding subs or extra audio without re-encoding.
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How to convert MP4 to MKV
Remux MP4 to MKV in three quick steps
1. Upload your MP4
Click “Upload” or drag a video onto the page. We handle HD and 4 K files up to 2 GB over secure HTTPS.
2. Choose MKV output
MKV is pre-selected for lossless remuxing. Keep every subtitle and audio track, or deselect ones you don’t need.
3. Download the MKV
Hit “Convert”. In seconds your new .mkv file is ready - no quality loss, ready for Plex, VLC or backup drives.
Keep subs & multi-audio
MKV stores unlimited subtitle and audio tracks. Our converter remuxes them intact - ideal for bilingual movies or commentary.
Future-proof container
MKV is open, patent-free and supported by VLC, Plex, Kodi and more. Also convert to WebM, AVI, FLV and audio formats in the same interface.
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FAQ
Why convert MP4 to MKV?
MKV supports multiple audio streams, soft subtitles, chapter markers and advanced codecs, making it ideal for archiving or media servers.
Will the video be re-encoded?
By default we perform a lossless remux - no re-encoding, so quality and bitrate remain identical to the source MP4.
Can I add external subtitles during conversion?
Not yet. The current version keeps existing subtitle tracks but doesn’t embed new ones; you can add them later with tools like MKVToolNix.
Is MKV compatible with my TV or console?
Most modern smart TVs, media boxes (Roku, Fire TV) and players like VLC and Plex handle MKV. Older devices may need MP4.
What is the maximum file size?
You can upload videos up to 2 GB. Larger files convert more slowly but follow the same secure workflow.
How secure are my files?
All transfers use HTTPS. Files are processed in volatile memory and automatically deleted within minutes of conversion.