Convert MP4 to MKV Online Free
Drag & drop your .mp4 file here, or click to browse
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Convert MP4 to MKV to take advantage of Matroska's superior container features including multiple audio tracks, embedded subtitles, and chapter support.
By ChangeThisFile Team · Last updated: March 2026
ChangeThisFile repackages your MP4 video into the MKV container using FFmpeg on our secure servers. MKV supports multiple subtitle tracks, audio streams, and richer metadata than MP4. Your file is processed and auto-deleted within seconds, free to use without any registration.
MP4 vs Matroska: Format Comparison
Key differences between the two formats
| Feature | MP4 | MKV |
|---|---|---|
| Standard | MPEG-4 Part 14 (ISO) | Matroska (open standard) |
| Audio tracks | Limited multi-track support | Unlimited audio tracks |
| Subtitles | Limited (TX3G, SRT) | Multiple subtitle formats (SRT, ASS, SSA, PGS) |
| Chapters | Basic chapter support | Full chapter support with titles |
| Error recovery | Less resilient | Designed for resilience and streaming |
| DRM | Common (MPEG-CENC) | Rarely used |
| Compatibility | Universal | Wide support (VLC, Kodi, media centers) |
When to Convert
Common scenarios where this conversion is useful
Adding external subtitle tracks
MKV supports embedding multiple subtitle files (SRT, ASS) directly in the container. Convert MP4 to MKV to add foreign language subtitles or forced subtitles to your video.
Media center and Kodi playback
Kodi, Plex, and most home media center software work natively with MKV. Convert MP4 collections to MKV for consistent playback with full subtitle and chapter support.
Preserving multiple audio languages
MKV allows unlimited audio tracks. Convert MP4 to MKV and add dubbed audio tracks in multiple languages for international content distribution.
Archiving full feature films
MKV is the standard format for archiving Blu-ray and DVD content, preserving all original audio, subtitle tracks, and chapter markers in a single file.
Fan-made video projects
Video hobbyists use MKV to combine video with custom subtitle tracks, commentary audio, and chapter navigation for fan edits and video essays.
Who Uses This Conversion
Tailored guidance for different workflows
Content Creators
- Convert MP4 footage to Matroska for playback in software and devices that expect the Matroska format
- Transform MP4 recordings to Matroska to match the format an existing workflow or player requires
Video Editors
- Convert MP4 footage to Matroska for importing into editing software like Premiere or DaVinci Resolve
- Transform MP4 project exports to Matroska for client delivery or final distribution
Social Media Managers
- Convert MP4 videos to Matroska for compatibility with legacy players or archival systems that use Matroska
- Transform MP4 source files to Matroska when a specific tool only accepts Matroska input
How to Convert MP4 to Matroska
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1
Upload your MP4 file
Drag and drop your .mp4 file onto the converter, or click to browse. The free tier accepts files up to 25MB; eligible paid browser access accepts up to 100MB.
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2
Server-side conversion
Your file is securely uploaded and remuxed into MKV using FFmpeg. The video and audio streams are preserved without re-encoding. Processing takes a few seconds.
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3
Download the result
Click Download to save your converted .mkv file. The original and converted files are automatically deleted from our servers.
Developers: convert via API →
Frequently Asked Questions
No quality is lost. The conversion is a remux — the video and audio streams are copied directly into the MKV container without re-encoding.
MKV supports more subtitle formats, unlimited audio tracks, better chapter support, and is an open standard without patent encumbrances. It is preferred for archiving and media centers.
Most modern smart TVs (Samsung, LG, Sony) support MKV playback. Older TVs may not. VLC on any platform plays MKV reliably.
Yes. Tools like MKVToolNix allow you to mux in additional subtitle or audio tracks to an MKV file without re-encoding.
Yes. Files are transferred over HTTPS and automatically deleted from our servers after conversion. We do not access or store your content.
Since MP4 to MKV is a remux (no re-encoding), it is very fast — usually just a few seconds even for large files.
The free tier accepts files up to 25MB; eligible paid browser access accepts up to 100MB.
Yes. MKV supports all resolutions including 4K and 8K, as well as HDR video (HDR10, Dolby Vision encoded in HEVC).
Yes, completely free. No signup, no subscription, unlimited conversions.
Yes. Windows Media Player supports MKV in Windows 10 and later. VLC plays MKV on all versions of Windows.
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Need to convert programmatically?
Use the ChangeThisFile API to convert MP4 to Matroska in your app or script. Free tier included.
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