What is the difference between MKV and MP4?

MKV and MP4 are both containers — they hold video, audio, and subtitle tracks. MKV supports more codecs and unlimited tracks. MP4 is more widely supported by devices and platforms. The video quality inside can be identical.

Will converting MKV to MP4 reduce quality?

Not if the MKV uses H.264 video and AAC audio — the conversion is a lossless remux. If the MKV uses a different codec, re-encoding is required, which may reduce quality slightly depending on the bitrate used.

Can I convert MKV files with subtitles?

The converter processes the first video and audio track. Embedded subtitle tracks are not included in the MP4 output. For subtitle support, use a desktop tool like HandBrake.

Are my video files uploaded?

No. All conversion runs in your browser via FFmpeg WebAssembly. Your MKV files never leave your device.

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Conversion

MKV to MP4 Converter Online Free

Convert MKV (Matroska) video files to MP4 for playback on iPhones, smart TVs, streaming platforms, and any device that doesn't support MKV. When the video is already H.264 and audio is AAC, the conversion is a fast lossless remux — no quality loss, just a container change.