Convert MP4 to MKV
Select Files
Audio, Video and Image supported. Drag or click
The fastest way to convert MP4 to MKV online: no software install, no account creation, no upload to third parties. Just open WeLoveConvert and go.
How It Works
Open the Upload Zone
Click anywhere in the upload area to browse your computer, or simply drag MP4 files in from your desktop.
Quick Browser Conversion
WeLoveConvert processes your files in seconds using your device hardware — no server queues, no slow uploads.
Ready to Download
Your converted MKV files appear in the download list as they finish. Save them locally with one click.
About These Formats
Converting MP4 to MKV unlocks a flexible Matroska container that can carry multiple audio tracks (original plus dubs), multiple subtitle tracks (SRT, ASS, embedded forced subs), chapters, tags, and rich metadata in a single file. This is exactly what home media libraries running Plex, Jellyfin, Emby, or Kodi want, and what audiophiles need when they want to preserve a lossless FLAC track alongside the standard AAC stream. Because both MP4 and MKV are just wrappers, you can usually remux MP4 to MKV without re-encoding the video at all — FFmpeg copies the H.264 or HEVC stream byte-for-byte into the MKV container, so the operation finishes in seconds with zero quality loss and the same file size. Beyond that, MKV adds robust error recovery: a corrupted MKV is far easier to play back partially than a damaged MP4. WeLoveConvert performs the convert MP4 to MKV step entirely in your browser using WebAssembly FFmpeg, so library-sized files never get uploaded. After conversion you can use MKVToolNix to merge in additional audio tracks or subtitle files without ever touching the video stream again.
Frequently Asked Questions
How do I convert MP4 to MKV?expand_more
Upload your files, confirm the conversion settings, and download your converted files. All processing happens in your browser — no server upload required.
Is this MP4 to MKV converter free?expand_more
Yes, completely free with no hidden fees. No sign-up required, no usage limits. All conversion happens in your browser.
Is it safe to convert MP4 to MKV online?expand_more
Your files never leave your device. All conversion happens locally in your browser using WebAssembly technology. We have zero access to your files.
Will I lose quality converting MP4 to MKV?expand_more
Quality depends on the target format and your settings. Lossless formats like PNG preserve original quality. For lossy formats like JPG, you can adjust the quality slider.
Can I convert multiple MP4 files at once?expand_more
Yes, you can convert multiple files at once. Simply drag all your files into the upload area or click to select them.
Common Issues
- infoMKV is not streamable in browsers — HTML5 video and most CDNs reject it, so do not use MKV for web publishing.
- infoiOS, Apple TV, Roku, and many smart TVs cannot play MKV natively without a third-party player like VLC or Infuse.
- infoAdding subtitle or chapter tracks requires a second tool (MKVToolNix) — FFmpeg alone only remuxes existing streams.
- infoSome Plex and Jellyfin clients will transcode MKV in real time, taxing your server CPU during playback.