Convert MP4 to MKV
Free, fast MP4 → MKV. No watermarks, no sign-up.
How to convert MP4 to MKV
1. Upload MP4
Drop your MP4 file into the converter above.
2. Confirm MKV
Output is already set to MKV. Adjust only if you need to.
3. Download
Convert and download your MKV file instantly.
Format Details
MP4
MP4 (MPEG-4 Part 14) is the most widely used digital video container format, storing H.264/H.265 video and AAC audio for web, mobile, and broadcast delivery.
videoMKV
MKV (Matroska Video) is a flexible open container that can hold multiple video, audio, and subtitle tracks in one file.
videoConverting MP4 to MKV: what actually changes
MP4 to MKV is one of the conversions this site performs, but the two formats are not interchangeable containers. Here is what the file keeps, what it loses, and how to get a result you can use.
What .MP4 and .MKV each hold
.MP4 is a video format built for playing, editing or re-encoding a clip, storing frames, bitrate and audio tracks. .MKV is a video format built for playing, editing or re-encoding a clip, storing frames, bitrate and audio tracks. Converting between them is a decision about which of those two jobs the result needs to do.
What changes in the conversion
Both files belong to the video category, so this is a like-for-like repackage: the same kind of content, stored in a different container. What changes is how .MKV encodes frames, bitrate and audio tracks — not what the file is about.
Quality and file size
Both .MP4 and .MKV are lossy formats. Each conversion re-compresses the file, so quality drops a little every round trip. Convert once from the original rather than chaining conversions.
When this conversion is the right one
Reach for .MKV when the software, device or platform you are sending to expects it — the content is the same video, only the packaging differs. The reverse direction works the same way, so you can always convert back from .MKV to .MP4 using the same tool.
Tips for a clean MP4 to MKV conversion
Start from the original file
Convert the .MP4 you started with, not an earlier .MKV output. Every extra round trip costs quality and can accumulate formatting drift.
Check the real type, not the extension
Video/mp4 becomes video/x-matroska. If a file was renamed rather than converted, it will fail to open — rename it back to its true extension before uploading and the conversion will recognise it.
Length decides the time
Conversion runs in real terms on duration: a few seconds of media finishes almost at once, while a full-length .MP4 takes noticeably longer. Upload once and let it finish rather than retrying.
Limits worth knowing
Uploads are capped per file (30 MB, or 100 MB for video) and processed temporarily — nothing is kept as a permanent copy. For huge video files, split or compress the source first.
Frequently Asked Questions
How do I convert MP4 to MKV?
Upload your MP4 file on Convertek, select MKV as the output format, then click Convert. Your MKV file will be ready to download instantly.
Is the MP4 to MKV converter free?
Yes. Converting MP4 to MKV on Convertek is completely free with no watermarks. Fair upload limits apply (typically 30 MB per file).
Is my file kept after conversion?
No. Files are processed temporarily and not stored permanently. Converted downloads are available only in your browser session.
What is the difference between MP4 and MKV?
MP4 and MKV are different file formats with distinct use cases. Converting between them lets you use your file in software or workflows that require the MKV format.