Does converting MP4 to MKV change video quality?

No. This conversion remuxes the streams (copies them directly) without re-encoding. The pixels and sound are identical to the original MP4. You won’t lose detail, color, or clarity.

How much does the file size change after converting?

Usually by less than 2%. For a 4-minute H.264/AAC MP4 (about 60 MB), the MKV will be almost the same size—sometimes a few KB smaller, sometimes larger, depending on container overhead.

Which devices and players support MKV?

MKV is supported by VLC, Kodi, Plex, most PC video editors, and some smart TVs. However, iPhone, iPad, and many Android gallery apps do not open MKV files natively. Always check compatibility before converting.

Can I convert MP4 to MKV with built-in OS tools?

Windows, macOS, and mobile OSes do not include a native MP4 to MKV converter. VLC can do remuxes, but it’s less user-friendly. QuickTime and Windows Photos do not export MKV at all. Videozify runs entirely in your browser and requires no install.

Will all subtitles and audio tracks be preserved?

Yes, as long as the streams are supported by MKV (almost all common ones are). The converter copies all tracks found in the MP4 into the MKV. No loss or change occurs during remuxing.

Is this process faster than re-encoding?

Yes. Remuxing is much faster because it just copies streams. A 4-minute file usually takes less than 10 seconds, depending on your device speed. Re-encoding would take much longer and could reduce quality.

Can I reverse the process and convert MKV back to MP4?

Yes, if the video and audio codecs in the MKV are compatible with MP4. Use our MKV to MP4 converter for a lossless remux back. Some advanced features or tracks may not transfer, as MP4 is more limited.

Does this tool compress or shrink my video?

No. Remuxing does not compress or shrink the video. The file size stays about the same. If you need a smaller file, use a video compressor after converting.

MP4 → MKV

MP4 to MKV Converter

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This MP4 to MKV converter repackages your MP4 video, audio, and subtitle streams into a Matroska (MKV) container. It does not re-encode or compress: the original quality and size are preserved. No data leaves your device. Just drop your MP4, convert, and download the MKV.

How to convert MP4 to MKV

Upload or drag your MP4 file into the box above.
Check the file details and confirm it’s the one you want to convert.
Click Convert. The process repackages your streams without re-encoding.
Download the finished MKV file to your device, with all tracks intact.

Why convert MP4 to MKV?

MP4 is the most widely used video container for phones, cameras, and editing software. It is the default for iPhone, Android, GoPro, Zoom recordings, and most consumer devices. But MP4 has some limits: it handles only a few audio and subtitle track types, and long files or exotic features (like multiple audio languages) can cause problems.

MKV (Matroska) is a flexible, open container. It supports almost any video or audio codec, multiple subtitle and audio tracks, chapters, and extra metadata. If you want to store or share a movie with different language tracks, or need to add advanced subtitles, MKV is often the better container. Many editors, Plex servers, and home theater systems prefer MKV for complex files.

Remuxing MP4 to MKV with this tool is lossless. The converter copies your video, audio, and subtitle streams directly—no re-compression, no generational quality loss. For a typical 4-minute H.264/AAC MP4 (around 40–80 MB), the MKV is usually within 1–2% of the original size. Sometimes the MKV is even a few kilobytes smaller, since Matroska’s overhead is lower.

There’s no point converting if your player or device only supports MP4. But if you need advanced features, want to avoid MP4’s restrictions, or plan to edit or archive your files, MKV is a solid choice.

If you need to reduce file size after converting, compress your MKV. To extract audio only, use the audio extractor.

MP4 vs MKV: what's the difference?

Property	MP4	MKV
Extension	.mp4	.mkv
Type	MPEG-4 container	Matroska (open) container
Typical size (4 min)	40–80 MB	40–80 MB (remux, no re-encode)
Audio/subtitle support	Limited (AAC, AC-3, SRT, few others)	Very broad (almost any codec/format)
Quality	Source picture and sound	Unchanged (remux)
Device support	Phones, browsers, TVs, editors	PCs, editors, Plex, Kodi, VLC, some TVs

MP4 is a container format used for most phones and cameras, suitable for basic video and audio. MKV (Matroska) is a flexible open container for video, audio, subtitles, and metadata, often used for archiving, editing, or advanced playback scenarios.

Does converting MP4 to MKV reduce quality?

No. This preset remuxes: it copies all video, audio, and subtitle streams from your MP4 into an MKV container without re-encoding. There’s no quality loss—pixels and sound remain identical. The tool does not offer a bitrate slider or compression setting because nothing is being compressed. If your MP4 was H.264 video with AAC audio, the MKV will have the same streams, just in a different wrapper.

Remuxing is fast and safe for compatible files. If your MP4 contains streams or features not supported by MKV (rare, but possible), the process will fail with an error. If you need to change codecs or compress, use a different tool. Keep the original MP4 until you’ve checked the MKV works as expected.

When should you NOT convert MP4 to MKV?

Don’t convert if you need to play the file on an older phone, TV, or device that only recognizes MP4. Some smart TVs, car stereos, and basic video editors won’t open MKV files at all. For social media uploads, stick with MP4. Also, if your MP4 is already simple (one video, one audio), and you don’t need extra features, converting to MKV gives no practical benefit.

MKV is great for archiving, editing, or home theater use, but compatibility is not universal. Always check your target device or app supports MKV before converting. If you need to shrink file size or change resolution, use a compressor or resizer tool instead—remuxing won’t make the file smaller.

Frequently asked questions

Does converting MP4 to MKV change video quality?: No. This conversion remuxes the streams (copies them directly) without re-encoding. The pixels and sound are identical to the original MP4. You won’t lose detail, color, or clarity.
How much does the file size change after converting?: Usually by less than 2%. For a 4-minute H.264/AAC MP4 (about 60 MB), the MKV will be almost the same size—sometimes a few KB smaller, sometimes larger, depending on container overhead.
Which devices and players support MKV?: MKV is supported by VLC, Kodi, Plex, most PC video editors, and some smart TVs. However, iPhone, iPad, and many Android gallery apps do not open MKV files natively. Always check compatibility before converting.
Can I convert MP4 to MKV with built-in OS tools?: Windows, macOS, and mobile OSes do not include a native MP4 to MKV converter. VLC can do remuxes, but it’s less user-friendly. QuickTime and Windows Photos do not export MKV at all. Videozify runs entirely in your browser and requires no install.
Will all subtitles and audio tracks be preserved?: Yes, as long as the streams are supported by MKV (almost all common ones are). The converter copies all tracks found in the MP4 into the MKV. No loss or change occurs during remuxing.
Is this process faster than re-encoding?: Yes. Remuxing is much faster because it just copies streams. A 4-minute file usually takes less than 10 seconds, depending on your device speed. Re-encoding would take much longer and could reduce quality.
Can I reverse the process and convert MKV back to MP4?: Yes, if the video and audio codecs in the MKV are compatible with MP4. Use our MKV to MP4 converter for a lossless remux back. Some advanced features or tracks may not transfer, as MP4 is more limited.
Does this tool compress or shrink my video?: No. Remuxing does not compress or shrink the video. The file size stays about the same. If you need a smaller file, use a video compressor after converting.