MP4 to MKV Converter

Convert MP4 to MKV online, for free.



Choose Files
  • From Device
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  • From OneDrive
  • From Url
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Video Options
Choose a codec to encode or compress the video stream. To use the most common codec, select "Auto" (recommended). To convert without re-encoding video, choose "Copy" (not recommended).
Choose how you want to adjust your video dimensions. If you select resolution or aspect ratio, the original video's width will be used to calculate the new height according to the chosen aspect ratio.
Change FPS (frames per second) of video
Video will be rotated clockwise.
Subtitle Settings
Select the best option for your subtitles: 'Upload' to add your own, or 'Copy' to replicate from the original file.
Choose a file Browse
Upload a .srt or .ass file.
Hardsubs, always visible and integrated into the video, are suitable for permanent captions, while softsubs, stored separately, can be turned on or off for customized viewing.
Audio Options
Choose a codec to encode or compress the audio stream. To use the most common codec, select "Auto" (recommended). To convert without re-encoding audio, choose "Copy" (not recommended).
100% represents the original volume. To double the volume, increase it to 200%. To reduce volume by half, select 50%
Trim Settings
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Specify the start position of trim (HH:MM:SS). Leave at 00:00:00 to disable.
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Specify the end position of trim (HH:MM:SS). Leave at 00:00:00 to disable.
Video Crop Settings
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Enter dimension numbers in pixels (0 - 10000). Odd dimension numbers will be rounded down to the nearest even number.


How to Convert MP4 to MKV?

  1. Click the “Choose Files” button to select your MP4 files.
  2. Click the “Convert to MKV” button to start the conversion.
  3. When the status change to “Done” click the “Download MKV” button

Easy to Use

Simply upload your MP4 files and click the convert button. You can also batch convert MP4 to MKV format.

Best Quality

We use both open source and custom software to make sure our conversions are of the highest quality. In most cases, you can fine-tune conversion parameters using “Advanced Settings” (optional, look for the icon).

Free & Secure

Our MP4 to MKV Converter is free and works on any web browser. We guarantee file security and privacy. Files are protected with 256-bit SSL encryption and automatically delete after a few hours.



Your Data, Our Priority

At FreeConvert, we go beyond just converting files—we protect them. Our robust security framework ensures that your data is always safe, whether you're converting an image, video, or document. With advanced encryption, secure data centers, and vigilant monitoring, we've covered every aspect of your data's safety.

Learn more about our commitment to security
  • SSL/TLS Encryption SSL/TLS
    Encryption
  • Secured Data Centers Secured Data
    Centers
  • Access Control and Authentication Access Control and
    Authentication

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