Convert MP4 to MKV for advanced features. MKV supports multiple audio tracks, subtitles, and chapters in a single file, perfect for archiving and media servers.
Percentage is applied to the original file size.
When converting to MKV, you can choose from avc, hevc, vp9, vp8, av1 for video encoding and aac, opus, mp3, vorbis for audio. We recommend H.264 (AVC) for maximum compatibility or H.265 (HEVC) for better compression.
This conversion happens entirely in your browser using WebCodecs API. Your videos never leave your device - there are no uploads to our servers or anyone else's. It's completely private and local.
When using the same or better codec with appropriate bitrate settings, converting MP4 to MKV can be done with minimal to no quality loss. Our tool lets you control the compression level to find the right balance between file size and quality.
Yes, this tool is completely safe because your videos never leave your device. The conversion happens entirely in your browser using WebCodecs API - nothing is uploaded to any server. Your files remain private on your computer.
Conversion time depends on your video length and computer speed. Most videos under 10 minutes convert in less than 2-3 minutes. The process is hardware-accelerated when your device supports it, making it significantly faster.
Yes! This tool works on iPhone (using Safari) and Android phones (using Chrome). The conversion happens right on your phone, so you can convert videos without uploading them anywhere.
For maximum compatibility, use H.264 (AVC). For better compression and smaller files, use H.265 (HEVC) if your target devices support it. The tool defaults to H.264 for the widest device support.