MKV to MP4
Convert MKV files to MP4, the format that plays everywhere. When the video is already H.264, it’s repackaged in seconds without losing any quality.
Your file will appear here.
First use downloads the video engine once (about 31 MB). After that it’s cached and starts instantly.
Fast copy vs re-encode
MKV (Matroska) is common for downloaded and recorded video, but many phones and editors don’t open it. If the video inside is already H.264 (the most common codec), the tool simply moves it into an MP4 container. That takes seconds and loses no quality. Otherwise it re-encodes to H.264 with AAC audio, which plays on every phone, browser and TV but takes longer.
How to use the MKV to MP4
- Choose a MKV file.
- Keep Automatic for the fastest result, or force a re-encode for maximum compatibility.
- Click Convert to MP4 and download the result.
Frequently asked questions
Is my video uploaded to a server?
No. The conversion runs inside your browser using a WebAssembly version of FFmpeg, the same engine professional video tools use. Your file never leaves your device.
Why does it take longer than desktop software?
It runs on a single processor core inside your browser, so re-encoding is slower than native apps. Conversions that can copy the original streams (no re-encoding) take only seconds.
Will I lose quality?
Not with a fast copy, which keeps the original data. Re-encoding at “High” or “Balanced” is visually very close to the original.