Convert MKV files to universally compatible MP4 right in your browser. Choose instant remux for zero quality loss, or re-encode with full control over quality and resolution. Fast, private, and free.
Drop your MKV video here or click to browse
Select a MKV video file
Drop your MKV file — or any other video format you need to convert.
Fast Copy for instant remux, or Re-encode for full quality and resolution control.
Get your converted MP4 instantly — plays on every device and platform.
Both MKV and MP4 are container formats that hold video, audio, and subtitle streams. MKV (Matroska) supports more codecs and features like multiple subtitle tracks, but MP4 is universally supported across all devices, browsers, and media players. Converting MKV to MP4 ensures your video plays everywhere.
Fast Copy (remux) simply repackages the video and audio streams from MKV into an MP4 container without re-encoding. It is nearly instant and causes zero quality loss. Re-encode converts the video to H.264 and audio to AAC, which takes longer but guarantees compatibility and lets you adjust quality and resolution.
With Fast Copy mode, there is absolutely zero quality loss — the original video and audio data are preserved bit-for-bit. With Re-encode mode, the "High" quality preset produces results nearly indistinguishable from the original. You can choose lower quality presets if you need a smaller file size.
Since conversion runs entirely in your browser using WebAssembly, the limit depends on your device's available memory. Most modern devices handle videos up to 500 MB–1 GB comfortably. Fast Copy mode uses less memory than Re-encode mode.
No. The entire conversion process happens locally in your browser using FFmpeg.wasm. Your video never leaves your device — it is 100% private.
MKV to MP4 conversion works in all modern browsers that support WebAssembly and SharedArrayBuffer — including Chrome, Edge, Firefox, and Safari 16.4+. For the best performance, use the latest version of Chrome or Edge.
Drop an MKV and get a universal MP4 in seconds — right in your browser, no sign-up required.