Toolsvana→Video & Audio Tools→Convert MP4 to MKV

Convert MP4 to MKV

Convert MP4 video files to MKV format

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Upload MP4 File

Choose an MP4 video file to convert to MKV

Maximum file size: 500MB

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Advanced Features

MKV supports multiple audio tracks and subtitles

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Open Standard

MKV is an open-source container format

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Flexible Storage

Store multiple streams and metadata efficiently

Free Online MP4 to MKV Converter

Our MP4 to MKV converter transforms your MP4 video files into the versatile Matroska (MKV) container format. MKV is an open-standard multimedia format that supports multiple audio tracks, subtitle streams, chapter markers, and metadata within a single file, making it ideal for media libraries and home theater setups.

The online video format converter offers dual processing modes: GPU-accelerated client-side conversion for fast, private processing and server-side FFmpeg conversion for broad codec support. Both modes preserve your video quality with customizable output settings including quality presets and codec selection.

Whether you need to store multiple audio languages, embed subtitles, or take advantage of the MKV container format's advanced features, our converter handles the job without requiring software downloads. With support for H.264, H.265, VP9, and AV1 codecs, you get maximum flexibility for your video projects.

Key Features

High-quality MP4 to MKV conversion with preserved video and audio fidelity
GPU-accelerated client-side processing using WebCodecs API
Server-side FFmpeg conversion with H.264, H.265, VP9, and AV1 codec options
Quality presets: Low, Medium, High, and Lossless output options
MKV container support for multiple audio tracks and subtitle streams
Original resolution, frame rate, and metadata preservation
Real-time progress tracking with processing statistics
Video preview and information display before conversion
Automatic server-side fallback when GPU mode is unavailable
Support for MP4 files up to 500MB

How to Use the MP4 to MKV Converter

Upload your MP4 file: Click "Choose MP4 File" to select a video file from your device (up to 500MB supported).
Review video details: Examine the displayed video information including format, duration, resolution, and file size.
Choose settings: Select your preferred output quality and video codec. Toggle GPU acceleration based on your browser's capabilities.
Convert to MKV: Click "Convert to MKV" and watch the progress bar as the conversion runs. Processing stats are shown upon completion.
Download the MKV file: Review the conversion summary comparing input and output details, then click "Download MKV" to save the file.

Use Cases

Home theater libraries: Convert MP4 files to MKV to take advantage of multiple audio tracks and embedded subtitle support for media server playback.
Multi-language content: Store multiple audio language tracks in a single MKV file instead of managing separate files for each language.
Subtitle embedding: Package subtitle files directly into the MKV container for convenient playback without separate subtitle file management.
Media archiving: Use MKV's open-standard format and lossless options for long-term video archiving with maximum quality preservation.
Video editing workflows: Convert to MKV for editors that prefer the format's flexible stream handling and chapter marker support.
Streaming media servers: Prepare content for Plex, Jellyfin, and Kodi which offer excellent MKV playback and metadata handling.
Codec flexibility: Re-encode using VP9 or AV1 codecs within the MKV container for better compression while maintaining visual quality.

Frequently Asked Questions

Is this tool free?

Yes, the MP4 to MKV converter is completely free with no hidden fees, watermarks, or conversion limits. You can convert as many videos as you need.

Is my data secure?

With GPU acceleration enabled, all processing happens in your browser and files never leave your device. Server-side conversions use secure uploads, and files are automatically deleted after processing.

Why convert MP4 to MKV?

MKV offers superior container features including support for unlimited audio tracks, subtitle streams, chapter markers, and metadata. It is an open-standard format widely supported by media players like VLC, Kodi, and Plex.

Which codec should I choose?

H.264 offers the best compatibility across devices. H.265 provides better compression for smaller files. VP9 is an open-source alternative, and AV1 offers the best compression but requires more processing time.

Will the conversion affect video quality?

Using "High" or "Lossless" quality settings preserves your original video quality. Lower quality settings reduce file size with minimal visible quality loss for most viewing scenarios.

Tips & Best Practices

Use GPU acceleration: Enable GPU mode for faster conversion and better privacy. It processes video locally without uploading to any server.
Select the right codec: For maximum compatibility choose H.264. For smaller file sizes with modern players, choose H.265 or VP9.
Try lossless first: If file size is not a concern, the lossless option preserves every detail of your original video during the conversion.
Check player compatibility: Ensure your target media player supports MKV format. VLC, Kodi, Plex, and most modern players handle MKV natively.
Compare file sizes: After conversion, review the before/after file sizes shown in the summary to verify the result meets your storage requirements.
Use server mode for complex files: If GPU conversion fails on certain MP4 files, switch to server-side mode which uses FFmpeg for broader codec support.