Why convert MP4 to MKV?
Converting from MP4 Video (MP4) to Matroska Video (MKV) is a common need in daily workflows. Whether you need a more compatible video container, smaller file sizes for web streaming, or want to extract audio from videos, choosing the right format matters.
With OmniConvert, the entire MP4 to MKV conversion process happens right in your browser using FFmpeg.wasm. No need to install desktop software like HandBrake or FFmpeg CLI, no file uploads to servers, and your video files remain 100% private. The first conversion loads the FFmpeg engine (~25MB), then subsequent conversions reuse the cached engine.
Key Benefits of OmniConvert
Privacy Protected
Your MP4 files are converted locally in your browser. Never uploaded to servers.
Fast & Free
No waiting queues, no subscriptions. Convert unlimited files.
High Quality
Advanced algorithms ensure your MKV output preserves the highest quality.
Works Offline
Functions without internet after initial load via PWA support.
How to Use
Drag and drop your MP4 file into the conversion area above.
The browser processes the conversion instantly — no waiting required.
Click the download button to save your new MKV file.
MP4 vs MKV: Quick Comparison
| Feature | MP4 | MKV |
|---|---|---|
| Compression | Lossy (H.264/H.265) | Various (H.264/H.265/VP9) |
| Transparency | No | Codec-dependent |
| Color Depth | 8/10-bit | 8/10/12-bit |
| Animation | Video | Video |
| Best For | Universal video playback, web streaming, mobile | Media storage, multiple tracks, subtitles |
Understanding MP4 and MKV Formats
MP4 is best suited for universal video playback, web streaming, mobile. It uses lossy (h.264/h.265) compression and does not support transparency. On the other hand, MKV excels at media storage, multiple tracks, subtitles, using various (h.264/h.265/vp9) compression and supporting transparency. Understanding these differences helps you choose the right format for each project and workflow.
Common Use Cases for MP4 to MKV Conversion
Content creators converting MP4 to MKV for social media platforms and video sharing websites.
Video editors preparing footage in MKV format for editing software compatibility.
Reducing video file sizes by converting MP4 to more efficient MKV format for web streaming.
Ensuring cross-platform playback compatibility by converting videos to the widely-supported MKV format.
Pro Tips for MP4 to MKV Conversion
OmniConvert uses FFmpeg.wasm for video conversion — a powerful, industry-standard tool running right in your browser.
The first video conversion downloads ~25MB of FFmpeg core files, but subsequent conversions reuse the cached engine.
Video transcoding can take 30 seconds or more for 1-minute videos — be patient, it's all happening locally on your device.