MP4 to MKV Video Converter
Drop your MP4 files — the MKV video is generated in your browser in seconds. Multiple files at once, no upload on the fast path.
9,214+ video files converted
This tool turns your video into MKV entirely in the browser. Flexible Matroska container that holds almost any codec plus multiple audio and subtitle tracks. You can convert several files at once, and because the fast path is local there is no upload step and nothing to clean up afterwards.
Looking to programmatically convert MP4 to MKV?
Same engine, available as a JSON API. Drop a file or URL via REST and get the converted video back — no browser, no UI, no rate limits on paid tiers.
Fast response on common video pairs
Webhook delivery for batch jobs
Dozens of video format pairs supported
MP4 vs MKV: how they compare
The numbers and capabilities at a glance, so you know what you're trading.
MP4
- Year released
- 2001
- Compression
- H.264 (lossy)
- Transparency
- No
- Animation
- Yes (video)
- Browser support
- Universal
- Best for
- Sharing & streaming everywhere
MKV
- Year released
- 2002
- Compression
- Codec-dependent
- Transparency
- Codec-dependent
- Animation
- Yes (video)
- Browser support
- Players, limited browsers
- Best for
- High-quality archives
Real MP4 → MKV file sizes
We ran fixed video clips through this exact converter so you can see the typical size impact before converting your own files.
| Video sample | MP4 size | MKV size | Change |
|---|---|---|---|
| High motion | 263.0 KB | 253.8 KB | -3% smaller |
| Complex detail | 370.1 KB | 345.1 KB | -7% smaller |
Measured on synthetic 3s · 426×240 · 20 fps video clips with this converter on 2026-06-23. Real-world files vary with duration, resolution, codec and content.
Heads up before converting to MKV
What this specific conversion changes about your video.
Lossless when the codecs already fit
If your MP4 uses codecs MKV accepts, we remux (rewrap) it losslessly and instantly. A codec change re-encodes, which recompresses slightly.
Best practices for MKV
Small choices that keep your output sounding right.
- Play the MKV result back before deleting your original MP4.
- Pick a preset (Web, Mobile, High quality) to balance size and quality for your MKV.
The importance of a good video conversion
Why getting MP4 → MKV right matters more than you think.
Frequently asked
The basics everyone asks before dropping a track.
Convert MP4 to other formats
Convert other formats to MKV