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MP4 to MKV Converter

Convert MP4 videos to MKV format, supporting multiple audio tracks, subtitles, and chapters in a flexible container.

Free to use, no watermarks, runs in your browser—nothing uploads to our servers

Source file

Files are processed locally in your browser using WebAssembly.

Saved FFmpeg presets (stored locally)

Saved presets

Preset name

Quality (CRF)

Lower = better quality (0-51, default: 23)

Jump to helper sections

What is MKV format?

MKV (Matroska Video) is a flexible, open-source container format that supports multiple video, audio, and subtitle tracks in a single file. It's ideal for storing movies and TV shows with multiple language options.

Why convert MP4 to MKV?

MKV offers better support for multiple audio tracks, subtitles, and chapters. It's the preferred format for storing high-quality video with complex metadata and multiple streams.

Will conversion affect quality?

This tool can copy streams directly without re-encoding for faster, lossless conversion. You can also re-encode with quality settings if needed.

Report a bug

If this tool misbehaves, share a quick summary so we can investigate. We include the tool URL automatically—no need to copy and paste.